gcse chemistry (combined) - belper school
TRANSCRIPT
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GCSE CHEMISTRY (COMBINED) HIGHER REVISION (revised)
Name:…………………………………………………………………………………………………………….
P1 & P2
Summary sheets 3 Parts of an atom
4 Metallic and ionic bonding
5 Covalent bonding
6 Calculations
P1
Summary sheets 7 States and separation
8 Acids
9 Electrolysis
10 Extraction of metals
P2 Summary sheets 11 Groups
12 Energy & rates of reaction
13 The Earth’s atmosphere and hydrocarbons
P1 & P 2 Skills
14 Balancing equations
15 Writing balanced equations
16 Writing a plan
17 Significant figures & calculating rate
Atomic Structure 18-19 Revision Questions
20-22 Exam Questions
Ionic Compounds 23-23 Revision Questions
24 6 mark – electrical conductivity
25 6 mark – ion formation
Molecular
Compounds
25-26 Revision Questions
28-29 Exam questions – Ionic & Molecular
Calculation
Practice
30-31 Calculation help sheet
32-33 Calculation Practice (1)
34-35 Calculation Practice (2)
P1 Separation 36-38 Revision Questions
39-41 Exam Questions
42-43 Core Practical – Investigate the composition of inks
using simple distillation and paper chromatography
Acids 44-45 Revision Questions
46 Titrations
47-49 Exam Questions
50 Core Practical – Investigate the preparation of pure,
dry, hydrated crystals of copper sulphate starting
from copper oxide.
51 Core Practical – Investigate the change in pH on adding
calcium hydroxide or calcium oxide to a fixed volume of
hydrochloric acid
Electrolysis 52-53 Revision Questions
54-55 Core Practical – Investigate the electrolysis of copper
sulphate solution using inert and copper electrodes.
56-58 Questions
Metals 59-60 Revision Questions
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61-64 Exam Questions
P2 Groups 65-66 Revision Questions
67 6 mark – displacement reactions
68-69 Exam questions
Rates of Reaction 72-75 Revision Questions
76 6 mark – reaction rates
77-80 Exam questions
81-82 Core Practical – Investigate the effect of changing the
conditions of a reaction by measuring the production of
hydrogen and a colour change with sodium thiosulphate
solution
Fuels and Earth 83-84 Fuels and Earth Science
85-87 Exam Questions
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SKILLS – BALANCING EQUATIONS
1. ……..Al + ……….O2 2Al2O3
2. ……….Cu + O2 …….CuO
3. 2CH4 + ………O2 2CO + ……….H2O
4. Zn + ……..HCl ZnCl2 + H2
5. CaCO3 + ……….HCl CaCl2 + ………………..+ ……………………….
6. Fe2O3 + 3C ………….Fe + …………CO2
7. Complete the balanced equation for the reaction of butane, C4H8 with oxygen to form
carbon monoxide, CO and water.
C4H8 + 4O2
SKILLS – WRITING BALANCED EQUATIONS
1. Carbon monoxide reacts with oxygen, O2 to form carbon dioxide . Write the balanced
equation for this reaction.
2. The decomposition of hydrogen peroxide H2O2 produces oxygen and water. Give the
balanced equation for this reaction.
3. Zinc oxide, ZnO, reacts with dilute hydrochloric acid to form zinc chloride, ZnCl2 and
water. Write the balanced equation.
4. Write the balanced equation for the reaction of copper with oxygen to form copper
oxide CuO.
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5. Iron is extracted from iron oxide Fe2O3 by heating iron oxide with carbon to form iron
and carbon dioxide. Write the balanced equation.
6. Hydrocarbons react in excess oxygen to form carbon dioxide and water. Write the
balanced equation for the reaction of heptane C7H16 with excess oxygen.
7. Pentane, C5H12 burns completely in air to form carbon dioxide and water. Write the
balanced equation.
8. Copper chloride CuCl2 reacts with potassium hydroxide KOH to form copper hydroxide
Cu(OH)2 and potassium chloride. Write the balanced equation.
9. Hydrogen,H2 reacts with oxygen, O2 to form water under appropriate conditions.
Write the balanced equation.
10. Write the balanced equation for the reaction of hydrochloric acid with sodium
hydroxide.
11. Sulfur dioxide reacts with rainwater to form sulphurous acid, H2SO3. Sulfurous acid is
oxidised by oxygen in the air to form sulphuric acid. Write the balanced equation for
the oxidation of sulphurous acid by oxygen.
12. Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride,
carbon dioxide and water. Write the balanced equation for this reaction.
SKILLS – IDENTIFY X
1. C12H26 C2H6 + C6H12 + X
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SKILLS – WRITING A PLAN
What are you changing?
What are you measuring?
What are you using to make the measurements?
What have you kept the same?
Marble chips (calcium carbonate) react with hydrochloric acid to produce carbon dioxide.
Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide
Describe how you could use marble chips and a solution of hydrochloric acid to show that
changing the temperature of the hydrochloric acid changes the rate of this reaction.
Marble chips (calcium carbonate) react with hydrochloric acid to produce carbon dioxide.
Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide
Describe how you could use marble chips and a solution of hydrochloric acid to show that
decreasing the concentration of the hydrochloric acid changes the rate of this reaction.
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SKILLS – SIGNIFICANT FIGURES
Give the following numbers to 2 significant figures:
23.12
5.667
0.356
45.58
Give the following numbers to 3 significant figures
46.789
5.689
0.1234
55.88
Give the following numbers to 2 decimal places:
23.156
23.557
23.412
SKILLS – CALCULATING THE RATE OF A REACTION
Calculate the average rate of reaction in volume of gas per second in the first 20 seconds
Draw a tangent and calculate the actual rate of reaction at 20s.
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ATOMIC STRUCTURE
Describe how the Dalton model of an atom has changed over time.
Complete table:
mass charge Position
Proton
Neutron
Electron
Explain why atoms contain equal numbers of protons and electrons
Compare the size of nucleus of an atom to the overall size of the atom.
State where most of the mass of an atom is concentrated
Describe the mass number of an atom
Describe the atomic number of an atom
What is unique about each element?
What is an isotope?
If an atom has an atomic number of 9 and a mass number of 19 give the number of
protons, electrons and neutrons.
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Calculate the relative atomic mass of chlorine if the relative abundance of carbon-13 is
21% and of carbon-12 79%.
How did Mendeleev arrange the elements at the time?
How did Mendeleev use his table to predict the existence and the properties of some
elements not then discovered?
Explain how you can use the atomic number to find the position of an element in the
periodic table.
Give the name for the rows in the periodic table.
Give the name for the columns in the periodic table. Why were some elements placed in
the same column?
Where are the metals and non-metals in the periodic table?
Give the rules for finding the electron configuration of an element
Maximum number of electrons in the first shell =
Maximum number of electrons in the second shell =
Maximum number of electrons in the third shell =
If an element has the electron configuration of 2.8.5 what does this tell you about the
position of the element in the periodic table?
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1 There are about 90 natural elements, which scientists have classified in the periodic table.
The grid below represents an outline of the periodic table. The letters A to F represent the positions of six different
elements in the table.
aWhich two letters represent elements that are metals? _________ _________ (2)
b Which two letters represent elements that have the same number of electrons in the outer shell of their atoms?
________ ________ (2)
cWhich two letters represent elements that have the same number of electron shells in their atoms?
________ ________ (2)
2 a Complete the table below with information about the three subatomic particles.
d Name of particle Charge Relative mass Where found in atom
proton 1 inside nucleus
electron -1 /negligible orbiting the nucleus
neutron 0 1
(2)
b An atom of oxygen has an atomic number of 8 and a mass number of 18.
i Complete the diagram on the right by drawing electrons
in the appropriate places to show the electron
configuration of oxygen.
(2)
ii Give the electron configuration of an oxygen atom
____________ (1)
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3 a The element boron has two isotopes, boron-10 and boron-11.
Complete the table below with the missing information about these isotopes of boron.
Isotope Atomic number
Mass number
Number of ...
protons neutrons electrons
boron-10 5 10 5 5
boron-11 5 11 5 5
(2)
b Describe, in terms of protons and neutrons in atoms, what is meant by the term ‘isotope’.
(2)
c Boron and aluminium are both found in group 3 of the modern periodic table.
i State why these elements are in the same group in the modern periodic table.
(2)
ii Suggest what this tells you about the chemical properties of the two elements.
(1)
4 a Mendeleev left gaps in his periodic table, putting question marks in for the elements with atomic masses
68 and 70.
iii Why did Mendeleev leave gaps in his first periodic table?
(1)
iv Give two ways in which Mendeleev ordered the elements in his periodic table
(2)
b How are the elements ordered in the modern periodic table?
(1)
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5 The diagram below shows a model of a lithium atom.
a This lithium atom can be represented in the form 73Li. State the number of protons and neutrons in the nucleus
of a lithium atom.
(2)
b Atom A has a mass number of 239 and an atomic number of 93.
v State the number of protons, neutrons and electrons in Atom A.
(3)
6 The relative atomic mass of an element can be calculated from data on isotopic abundance.
a Calculate the relative atomic mass of copper, which has two isotopes: 69% is 63Cu, 31% is 65Cu
Show all of your working in the box below.
(2)
b The element boron has 2 isotopes: boron-10 and boron-11 – it has a relative atomic mass of 10.8
What does this tells us about the relative abundance of the two isotopes of boron?
(1)
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IONIC COMPOUNDS
What is an ion?
How do ions form?
Why do ions form?
What is the name for a positive ion?
What is the name for a negative ion?
Draw a dot and cross diagram to show the bonding in sodium chloride, NaCl. Sodium has an
electron configuration of 2.8.1. Chlorine has an electron configuration of 2.8.7.
Describe the structure of an ionic compound
Do ionic compounds have high or low melting points? Explain
When do ionic compounds conduct electricity? Explain
What does the ending IDE usually mean in an ionic compound?
What does the ending ATE usually mean in an ionic compound?
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Give the formulae of the following compounds have been given their ions.
Ions : O2-, SO42-, CO3
2-, Cl-, Br-, NO3-, Mg2+, Ca2+ Na+
Magnesium oxide
Calcium Sulphate
Sodium oxide
Magnesium chloride
Calcium nitrate
Magnesium bromide
Sodium chloride
Electrical conductivity of ionic compounds (H) Explain the difference in the ability of solid sodium chloride and molten sodium chloride to conduct electricity in terms
of their structures. (6)
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C2 Key Assessment Task Ion formation (H)
Magnesium has an electronic configuration of 2.8.2. Oxygen has an electronic configuration of 2. Explain, in terms of their electronic configurations, how magnesium and oxygen atoms react to form the ionic compound magnesium oxide, MgO, and include a description of the structure of solid magnesium oxide. (6) ……………………………………………………………………………………………………………………………………………………………………………
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MOLECULAR COMPOUNDS
What is a covalent bond?
Draw the dot and cross of H2
Electron configuration of H = 1
Draw the dot and cross of HCl
Electron configuration of H = 1, Cl= 2.8.7
Draw the dot and cross of CH4
Electron configuration of H = 1, C=2.4
Draw the dot and cross of H2O
Electron configuration of H = 1, O= 2.6
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Diamond - describe the bonding
Explain why it doesn’t conduct electricity
Give a use:
Graphite - describe the bonding.
Explain why it conducts electricity.
Give a use:
METALS
Label the diagram Explain why metals are malleable
Explain why metals conduct electricity
Draw the dot and cross of O2
Electron configuration of O = 2.6
Draw the dot and cross of CO2
Electron configuration of C = 2.4, O=2.6
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Sciences SC 5/6/7 BONDING
1. Many substances exist as molecules.
(a) The diagram shows the outer shell electrons in a molecule of methane CH4
Each hydrogen atom is bonded to the carbon atom by a covalent bond.
Give the meaning of the term covalent bond
……………………………………………………………………………….(2)
(b) Methane is a typical simple molecular, covalent compound. A property
of methane is that it has:-
A A high melting point
B It is a good conductor of electricity
C There are weak bonds in its molecule
D It has a low boiling point
2 (a). The electron configuration of oxygen (atomic number 8) is 2.6
Give the electronic configuration of carbon (atomic number 6)……………………………..
(b) Draw a dot and cross diagram of a molecule of carbon dioxide. Show the outer electrons only.
3.
sodium Sulphur
Metal or non metal metal Non-metal
Symbol Na S
Atomic number 11 16
Sodium sulphide is an ionic compound. Describe in terms of electron transfer how sodium atoms react with sulphur
atoms to form sodium sulphide. Your description should include the charges on the ions formed (4).
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4. The structures of diamond and graphite are shown below.
(i) State the maximum number of covalent bonds formed by a carbon atom in a diamond crystal ………………
(ii) Which of the following statements about diamond and graphite is true?
A – they are both good conductors of electricity
B – they are both soluble in water
C – they both cut glass
D – they both have high melting points
5. Oxygen is a simple molecular, covalent substance. The electronic configuration of oxygen is 2.6. Draw a dot and
cross diagram for a molecule of oxygen, O2. Show the outer electrons only.
6. Hexane is a covalent compound containing simple molecules. It has a low boiling point. Explain why it has a low
boiling point.
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SUMMARY OF METHODS FOR CALCULATIONS
1. Calculate Relative Formula Mass
You need to add up the masses of all the atoms in the formula.
2. Give empirical formula from molecular formula
You need find the simplest ratio. Decide whether each number can be divided by a common number
3. Calculate Empirical Formula
Calculate Mass (no of moles)
RAM
Divide by the smallest number
Give the empirical formula
4. Calculating theoretical mass
1. Calculate number of moles of the known (Mass/RAM)
2. Look at the ratio of the known:unknown
3. Rearrange the formula and use mass = moles x RAM
5. Calculate concentration in gdm-3
Convert cm3 into dm3 by dividing by 1000
Use concentration = mass
Volume (in dm3)
6. Calculate Rf values
Rf value = distance moved by solute
Distance moved by solvent
Rf values CANNOT be >1.
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7. Calculate number of moles
Number of moles = mass
RAM
8. Calculate the number of particles from number of moles
Number of particles = number of moles x Avogadro’s constant
You are given Avogradro’s constant of 6.02 x 1023
9. Calculate the number of particles from a mass
Calculate the number of moles first.
Then use number of particles = number of moles x Avogadro’s constant.
10. Calculating a balanced equation
This is the same method as empirical formula but instead of using the atoms of elements you need to use the fomula
in the equation.
Calculate number of moles of the substances
Divide by the smallest number
These values then give you the balancing numbers in an equation.
11. Identifying the limiting reactant.
Calculate the number of moles of one of the substances.
Then use the ratio to find the number of moles you need of the other.
Then calculate the number of moles of the other substance and compare to how much you need.
12. Calculating the energy change in a reaction
Calculate the energy of the reactants (LHS of the equation)
Calculate the energy of the products (RHS of the equation)
LHS – RHS
13. Calculate relative atomic mass of a samples.
Relative atomic mass = (% abundance of A x atomic mass of A) + (% abundance of B x atomic mass of B )
100
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REVISION CALCULATION QUESTIONS - COMBINED (1)
1.Calculate the relative formula mass
What is the relative formula mass of Ba (OH)2? (relative atomic masses: Ba=137, O=16, H=1)
2. Give the empirical formula from the molecular formula
If a sample has the molecular formula of C2H4 what is the empirical formula?
3.Calculate Empirical formula
A sample of nitrogen oxide contains 4.0g of nitrogen and 9.2g of oxygen. Calculate the empirical formula (relative
atomic masses: N=14, O = 16).
4. Calculating theoretical masses
CaCO3 + H2SO4 CaSO4 + H2O + CO2
If 55g of CaCO3 reacts what mass of CaSO4 is produced ? (relative atomic masses: Ca=40, C=12, O = 16, H =1, S=32)
5. Calculate concentrations in g dm-3
4.1g of sodium chloride is dissolved in 50cm3 of water. Calculate the concentration of the sodium chloride solution in
g dm-3.
6. Calculate Rf values in chromatography
If the solvent moves 10cm and the solute moves 6cm calculate the Rf value.
7. Calculation of number of moles (HIGHER ONLY)
How many moles are there in 42g of magnesium (relative atomic mass: Mg = 24)? Give the answer to 2 significant
figures.
8. Calculate number of particles (HIGHER ONLY)
Avogadro’s constant is 6.02 x 1023. How many potassium atoms are there in 0.8 moles of potassium?
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9.Calculate number of particles (HIGHER ONLY)
Avogadro’s constant is 6.02 x 1023. How many potassium atoms are there in 22 g of potassium? (relative atomic
mass: K=39)
10. Working out the balanced equation from given masses (HIGHER ONLY)
If 10.4g of sulphur reacts with 5.2g of O2, oxygen to form a sulfur oxide, use the masses to determine the LHS of the
balanced equation. (relative atomic masses: S=32, O=16)
11. Calculating limiting reactant (HIGHER ONLY)
Mg +2HCl MgCl2 + H2
If 1.3 g of magnesium reacts with 18.5g of hydrogen chloride, which is the limiting reactant? (relative atomic
masses: Mg = 24, Cl=35.5, H=1)
12. Calculate the energy change for the reaction using bond enthalpies
2H2 + O2 2H2O
Bond Energy KJ/mol
H-H 436
O=O 498
O-H 464
13. Calculate the Relative Atomic Mass of an element from the % abundances13. Calculate the Relative Atomic
Mass of an element from the % abundances
A sample contains 85.4% of carbon-12 and 14.6% of carbon-13. Use this information to calculate the relative atomic
mass of boron.
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REVISION CALCULATION QUESTIONS COMBINED (2)
1.Calculate the relative formula mass X
Calculate the relative formula mass of magnesium nitrate, Ca(NO3)2? (relative atomic masses: Ca = 40, N=14,O=16)
2. Give the empirical formula from the molecular formula
If a sample has the molecular formula of N3O6 what is the empirical formula?
3.Calculate Empirical formula
A sample of calcium iodide contains 0.2g of calcium and 1.3 g of iodine by mass. Calculate the empirical formula of
calcium iodide (relative atomic masses: Ca=40, I = 127).
4. Calculating theoretical masses
CuCO3(s) CuO (s) + CO2 (g)
35g of pure copper carbonate is decomposed completely. Calculate the maximum mass of the solid produced
(relative atomic masses: Cu=63.5, C=12, O = 16). Give your answer to 2 sig fig.
5. Concentrations in g dm-3
A potassium iodide solution contains 5.3 g of potassium iodide in 50cm3 of water. Calculate the concentration of the
potassium iodide solution in g dm-3.
6. Calculate Rf values in chromatography
If the solvent moves 15cm and the solute moves 10cm calculate the Rf value.
7. Calculation of number of moles (HIGHER ONLY)
Calculate the number of moles of sodium in 42g (relative atomic mass: Na= 23)? Give the answer to 2 significant
figures.
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8. Calculate number of particles (HIGHER ONLY)
Calculate the number of atoms in 0.6 moles of potassium? Avogadro’s constant is 6.02 x 1023)
9.Calculate number of particles (HIGHER ONLY)
Calculate the number of atoms in a 25g sample of potassium? (relative atomic mass: K=39) (Avogadro’s constant is
6.02 x 1023)
10. Working out the balanced equation from given masses (HIGHER ONLY)
In an experiment, 11.2g of iron reacts exactly with 76.2g of iodine, I2. Determine the balanced equation for the
reaction between iron and iodine. (Relative atomic masses: Fe=56, I=127)
11. Calculating limiting reactant (HIGHER ONLY)
2Li +2HCl 2LiCl + H2
If 3.5 g of lithium reacts with 16.5g of hydrogen chloride, which is the limiting reactant? (relative atomic masses:Li =
7, Cl=35.5, H=1)
12. Calculate the energy change for the reaction using bond enthalpies
2CH4 + 2O2 2CO2 + H2O
Bond Energy KJ/mol
C-H 413
O=O 498
O-H 464
C=O 799
13. Calculate the Relative Atomic Mass of an element from the % abundances
A sample contains 19.7% of boron-10 and 80.3% of boron-11. Use this information to calculate the relative atomic
mass of boron.
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SEPARATION
Describe the arrangement, movement and the relative energy of particles in a solid
Describe the arrangement, movement and the relative energy of particles in a liquid
Describe the arrangement, movement and the relative energy of particles in a gas
Give the names of the interconversions from solid -> liquid -> gas
Give the names of the interconversions from gas -> liquid -> solid
If a substance has a melting point of -20oC boiling point of 16oC what is its state at room
temperature 25oC?
If a substance has a melting point of -20oC and boiling point of 100oC what is its state at
room temperature 25oC?
What is the difference between the melting points of pure substances and mixtures
Heating curves. Describe the changes that are happening in the following curve.
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What is simple distillation used for?
Draw a labelled diagram of distillation
Describe the risks of using distillation to separate an ethanol-water mixture.
Draw a labelled diagram of filtration.
What is filtration used for?
Describe crystallisation.
Draw a diagram to show how to produce a chromatogram
Give the name of the solvent in chromatography
Give the name of the paper in chromatography
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Why do some compounds move to a higher position on the chromatography paper than
others?
Why do some dots not move on the chromatography paper?
Calculate the Rf value of a compound if the dot of the solute moves 4cm and the solvent
moves 6cm. Leave your answer to 2 significant figures.
What does potable mean?
How can river and waste water be made potable?
Who can sea water be made potable?
Why can’t sea water be used for chemical analysis?
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SEPARATION EXAM QUESTIONS
1.Substances can be pure or they can be mixtures. Which of the following is a mixture?
A Chlorine
B Sodium
C Sodium chloride
D Sodium chloride solution
2. The table shows some mixtures to be separated and some possible methods of separation. Place a tick in one box
in each row of the table to show the best method to separate the first named substance from each of the mixtures.
Substance to separate
Method of separation
Crystallisation Filtration Simple distillation Fractional distillation
Sand from a mixture of sand and sodium chloride solution
Copper sulphate crystals from copper sulphate solution
Useful liquids from crude oil
3. Paper chromatography was used to separate a mixture of blue and red inks. A spot of the mixture was placed on
chromatography paper as shown below.
(a) Give a reason why the start line is drawn in pencil rather than ink.
……………………………………………………………………………………………………………………………………………………………………………(1)
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The chromatography paper with the mixture on it was placed in a beaker with the bottom of the paper in the water.
Complete the diagram below showing the position of the chromatography paper with the spot of mixture at the start
of the experiment.
The chromatography was carried out and the result is shown below.
(b)The blue spot had moved 14.5cm and the solvent front had moved 15.3cm. Calculate the Rf value of the
substance in the blue spot. Give the answer to 2 significant figures.
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(c )If a spot does not move from the original pencil line, what information does this give about the substance in the
spot?
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4. The table shows the boiling point and melting point of naphthalene. Give the physical state of naphthalene at
225oC.
Melting Point oC Boiling Point oC
Napthalene 78 218
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5. A student heated a substance in a solid state. She measure the temperature of the substance every minute until a
few minutes after it melted. The student identified three different stages in how the substance looked. The graph
below shows the results of her experiment.
(a)Explain whether the results show the substance was a mixture or a pure substance.
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(b) What is the name given to stage B ………………………………………………………………………………………………………………..
6. The diagram below shows the three stages to treat fresh water to make it potable.
(a) State what happens during sedimentation ……………………………………………………………………………………………….
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(b)Explain why the water is not pure after the filtration stage
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(c ) Give a reason why the chlorination stage is necessary
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CORE PRACTICAL - Investigating Inks
Answer
What is the practical about?
What is the process called?
Name a hazard and a way to reduce the risk
What temperature does water boil at ?
What is the name given to the process when water vapour becomes a liquid?
Why is ice used ?
Draw particles diagrams to show the arrangement of particles in a solid, liquid and gas
SOLID
LIQUID
GAS
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PRACTICAL 2 - Chromatography
Section Answer
What is the practical
about?
Give the name of the
process
Describe how to create a
chromatogram
1.
2.
3.
Calculate the Rf value of
the purple spot
Calculate the Rf value of
the blue spot
If a spot on the pencil
line doesn’t move what
does it tell you about the
substance?
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ACIDS MAX TAYLOR
What does an acid contain?
H+
What ions do alkalis contain?
OH-
What is the pH of a neutral solution?
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When the pH of an acid reduces from 2 to 1 what does this say about the concentration?
X10
H What is meant by a dilute solution compared to concentrated solution?
Doesn’t contain many ions
H What is meant by a weak acid?
Partially ionises
H What is meant by a strong acid?
Totally ionises
What is a base?
Reacts with an acid
Complete the word equation and give the balanced equation
Hydrochloric acid + magnesium
Magnesium chloride + hydrogen
Complete the word equation and give the balanced equation
Nitric acid + calcium oxide calcium nitrate + water
Complete the word equation and give the balanced equation
Sulfuric acid + magnesium hydroxide magnesium sulphate + water
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LUCY
Complete the word equation and give the balanced equation
Hydrochloric acid + magnesium carbonate
Magnesium chloride + carbon dioxide + water
What is the test for hydrogen gas?
Lit splint makes squeaky pop
What is the test for carbon dioxide?
Bubble into limewater and turns cloudy
What is the name of the reaction between an acid and alkali?
Neutralisation
What is the ionic equation for a neutralisation reaction?
H+ + OH- H2O
46
TITRATIONS
List the equipment used in a titration –state what it is used for
-
-
-
-
-
-
-
INDICATORS IN A TITRATION
Colour in acid Colour in alkali
Methyl Orange
Phenol Phthalein
Why can’t Universal Indicator be used in a titration?
……………………………………………………………………………………………………………………………
……………………………………………………………………………………………………………………………
47
Questions on acids
Q1. Calcium nitrate solution can be made by adding solid calcium carbonate to dilute nitric acid in a beaker. The solid calcium carbonate is added until some remains at the bottom of the beaker.
(i) After this reaction the liquid in the beaker is
(1)
A acidic
B alkaline
C neutral
D pure water
(ii) Explain why the calcium carbonate is added until some solid remains at the bottom of the beaker.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(iii) Write the balanced equation for the reaction between calcium carbonate and nitric acid to form calcium nitrate, Ca(NO3)2.
(3)
.............................................................................................................................................
Q2. A solution of hydrochloric acid has a pH of 1.
Explain the pH change when 10 cm3 of this acid is diluted with water to make 100 cm3 of solution.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Q3. A student carried out an experiment to see how reactive different metals are when they are placed in dilute hydrochloric acid. A sample of each metal was placed in a separate test tube of acid. In the experiment, the student used the same amount of each metal in a finely powdered form.
State two factors, concerning the hydrochloric acid, which should also be controlled to produce valid results.
(2)
1 ..........................................................................................................................................
.............................................................................................................................................
2 ..........................................................................................................................................
.............................................................................................................................................
48
Q4. A student has been asked to investigate how the pH changes when calcium oxide is added, a little at a time, to dilute hydrochloric acid. Describe how the student should carry out this investigation.
(3)
.............................................................................................................................................
.............................................................................................................................................
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Q5. A strong acid reacts with a strong alkali to form a neutral solution.
Write the ionic equation for this reaction.
(2)
.............................................................................................................................................
Q6. A student carried out an experiment to see how reactive different metals are when they are placed in dilute hydrochloric acid.
A sample of each metal was placed in a separate test tube of acid.
When zinc reacts with dilute hydrochloric acid, a gas is given off and zinc chloride is formed.
(i) Which gas is given off?
A carbon dioxide
B chlorine
C hydrogen
D oxygen
(1)
(ii) What is the formula of zinc chloride?
A ZnCl
B Zn2Cl
C ZnCl2
D Zn2Cl2
(1)
Q7. Some acids such as hydrochloric acid are described as strong acids. Some acids such as ethanoic acid are described as weak acids.
(i) Explain the difference between a strong acid and a weak acid. (2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(ii) Give a reason why adding hydroxide ions to an acid solution leads to an increase in pH. (1)
.............................................................................................................................................
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49
Q8. Carbon dioxide can be formed by the reaction of magnesium carbonate, MgCO3, with dilute hydrochloric acid. Write the balanced equation for this reaction.
(3)
.............................................................................................................................................
Q9. The salt zinc nitrate can be made by reacting zinc oxide, ZnO, with dilute nitric acid, HNO3.
Write the balanced equation for this reaction.
(2)
.............................................................................................................................................
Q10. Sodium hydroxide, NaOH, can be reacted with dilute sulfuric acid, H2SO4, to form sodium sulphate and water. Write the balanced equation for this reaction.
(2)
.............................................................................................................................................. Q11. (a) A titration is used to determine the exact volumes of sulfuric acid and sodium hydroxide solution that neutralise each other. 25.00 cm3 of sodium hydroxide solution is put into a conical flask and a few drops of indicator solution are added. The sulfuric acid is added slowly from a burette until the indicator changes colour when all the sodium hydroxide is just neutralised.
(i) State what is used to measure out 25.00 cm3 of sodium hydroxide solution. (1)
.............................................................................................................................................
(ii) State the name of an indicator that could be used and the colour change seen in this titration.
(3)
Indicator .............................................................................................................................................
colour in sodium hydroxide solution ....................................................................................................
colour at end of titration .........................................................................................................................
50
CORE PRACTICAL - Preparing copper sulfate
Section Answer
What is practical about?
Give the 4 steps in the
method
M
S
F
E
Name the process when
the water is evaporated
to leave the crystals
Making a soluble salt from an acid and
insoluble reactant.
51
CORE PRACTICAL - Investigating Neutralisation
Section Answer
What is practical about?
Give the method
1.
2.
3.
How do you measure
the pH?
52
ELECTROLYSIS
What is an electrolyte?
What is electrolysis?
What is the name of the negative electrode?
What is the name of the positive electrode?
Which ions (cations or anions) move to the cathode?
Which ions (cations or anions) move to the anode?
What are the 2 ions present in water?
Electrolyte
Product formed at the anode Product formed at the cathode
Molten lead bromide
Molten sodium chloride
Acidified water
Sodium chloride solution
Sodium sulphate solution
Copper sulphate solution (inert electrodes)
53
At the anode: A sulphate solution doesn’t break down so Oxygen forms from Hydroxide in the water
At the cathode: The lest reactive element forms
O
I
L
R
I
G
In molten lead bromide, the Pb2+ forms Pb and Br2 forms from Br-. Complete the half equations. State which is
oxidised and which is reduced. Explain.
Pb2+
Br-
In molten sodium chloride, the Na+ forms Na and Cl2 forms from Cl-. Complete the half equations. State which is
oxidised and which is reduced. Explain.
Na+
Cl-
In acidified water, H2 forms from H+ and O2 forms from OH-. Complete the half equations. State which is oxidised and
which is reduced. Explain.
H+
OH-
In sodium chloride solution, H2 forms from H+ and Cl2 forms from Cl-. Complete the half equations. State which is
oxidised and which is reduced. Explain.
H+
Cl-
In sodium sulfate solution, H2 forms from H+ and O2 forms from OH-. Complete the half equations. State which is
oxidised and which is reduced. Explain.
H+
OH-
In copper chloride solution, Cu forms from Cu+ and Cl2 forms from Cl-. Complete the half equations. State which is
oxidised and which is reduced. Explain.
Cu+
Cl-
54
CORE PRACTICAL - Electrolysis of copper sulfate solution - using copper electrodes
Section Answer
What is practical about?
Which electrode increases in mass?
Explain the change in mas
Describe the relationship between the change in mass and the current
Give the half equation for the cathode
Give the half equation for the anode
55
CORE PRACTICAL - Electrolysis of copper sulfate solution - using inert electrodes
Section
Answer
What is the practical about?
Cooper is formed at the cathode. Give the half equation
Oxygen is formed at the anode. Give the half equation
56
ELECTROLYSIS QUESTIONS Q1. (i) When copper sulfate solution is electrolysed using inert electrodes, oxygen is formed at the positively charged anode. Explain how the oxygen is formed from ions in the solution.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. Q2. The ions in sodium chloride solution are
sodium ions, Na+ chloride ions, Cl– hydrogen ions, H+ hydroxide ions, OH– Sodium chloride solution is electrolysed using a direct electric current. (i) Which of these ions will be attracted to the cathode during the electrolysis of sodium chloride solution?
Put a cross ( ) in the box next to your answer. (1)
A H+ ions only
B H+ and Na+ ions
C Cl– ions only
D Cl– and OH– ions (ii) Chlorine is one of the products of the electrolysis.
The half-equation for the production of chlorine is 2Cl– → Cl2 + 2e
Explain how the half-equation shows that chloride ions are oxidised. (2)
..............................................................................................................................................
.............................................................................................................................................. (iii) Suggest why the solution remaining at the end of the electrolysis is alkaline.
(1)
..............................................................................................................................................
.............................................................................................................................................. (iv) The electrolysis of sodium chloride solution does not produce metallic sodium.
State what change you would make to the electrolyte to obtain metallic sodium. (1)
..............................................................................................................................................
.............................................................................................................................................. Q3.(a) Copper sulfate solution was electrolysed using copper electrodes. The mass of each electrode was determined before it was placed in the solution.
57
The electrolysis was carried out for a period of time. The electrodes were removed, washed, dried and their masses redetermined. The table shows the masses of the electrodes before and after electrolysis.
Explain these results.
(3)
.............................................................................................................................................
.............................................................................................................................................
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............................................................................................................................................. (c) In an electrolysis experiment, oxide ions, O2−, form oxygen gas, O2.
Write the balanced half equation for the reaction. (2)
............................................................................................................................................. (d) Sodium chloride is an ionic compound. It contains sodium ions, Na+, and chloride ions, Cl−.
When molten sodium chloride is electrolysed, sodium metal and chlorine gas are formed. Describe how the sodium ions and chloride ions in solid sodium chloride are converted into sodium and chlorine by electrolysis.
(6)
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58
Q4.(a) Molten lead bromide is electrolysed.
(i) Complete the sentence describing the type of reaction.
(1) During the electrolysis the lead ions gain electrons at the cathode. The type of reactions in which metal ions gain electrons is called .....................................................
(ii) Complete the sentence by putting a cross ( ) in the box next to your answer. Molten lead bromide, rather than solid lead bromide, has to be electrolysed because
(1)
A ions can only move freely in molten lead bromide
B electrolysis is too fast in solid lead bromide
C molten lead bromide contains free electrons
D lead bromide has a very low melting point (iii) When molten lead bromide is electrolysed, a silver-coloured liquid is produced at the cathode and a red-brown gas is produced at the anode. Complete the word equation by showing the products formed when molten lead bromide is electrolysed. (2)
lead bromide → ..................................................... + .....................................................
Q5. Water decomposes into hydrogen and oxygen during electrolysis. A sample of water is electrolysed. The hydrogen and oxygen are collected separately. After 10 minutes the volumes of hydrogen and oxygen are measured.
Two further experiments are carried out, changing only one factor in each experiment. All other factors are kept the same. The table below shows the conditions and results for all three experiments.
Experiment Time (mins) Current (Amps) Volume of hydrogen (cm3)
Volume of oxygen (cm3)
1 5 0.50 20.0 10.0
2 10 0.50 40.0 20.0
3 5 0.75 30.0 15.0
Analyse this data to explain the effect of changing the time and the current on the volumes of hydrogen and oxygen produced.
59
EXTRACTING METALS AND EQULIBRIA
How are reactive metals found on Earth?
How are unreactive metals found on Earth?
What is oxidation in terms of oxygen?
What is reduction in terms of oxygen
How do you extract reactive metals such as aluminium from their ores?
How do you extract less reactive metals such as iron from their ores?
H Describe bacterial extraction
H Describe phytoextraction
What are the advantages of recycling metals?
What factors should you include in the lifetime assessment of a product?
60
What is meant by a dynamic equilibrium?
In the formation of ammonia where do the nitrogen and hydrogen come from?
What are the conditions of the Haber process?
H For the Haber Process, how will the position of dynamic equilibrium change with increased
temperature?
H For the Haber Process, how will the position of dynamic equilibrium change with increased
pressure?
H For the Haber Process, how will the position of dynamic equilibrium change with increased
concentration?
61
METAL EXTRACTION QUESTIONS Q1. Iron is extracted from iron oxide, Fe2O3. In the extraction process the iron oxide is heated with carbon to form iron and carbon dioxide. Write the balanced equation for this reaction.
(3)
.............................................................................................................................................
Q2. Complete the sentence by putting a cross ( ) in the box next to your answer.
The reaction for the extraction of aluminium from its ore involves (1)
A heating with carbon
B thermal decomposition
C reduction
D neutralisation Q3. The list shows some metals in order of reactivity.
(a) Aluminium and iron are extracted by reduction of their oxides.
State what is meant by reduction. (1)
.............................................................................................................................................
.............................................................................................................................................
(b) Electrolysis and heating with carbon are two methods of reduction.
Explain why aluminium needs to be extracted from its ore by electrolysis, rather than by heating with carbon.
(2)
.............................................................................................................................................
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.............................................................................................................................................
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62
Q4. Impure copper is purified by electrolysis using the apparatus shown.
(i) Give the name of the electrode which is made of pure copper.
(1)
.............................................................................................................................................
(ii) Describe how each electrode will have changed at the end of the electrolysis process.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(iii) Complete the sentence by putting a cross ( ) in the box next to your answer.
Cu2+(aq) + 2e− → Cu(s)
This half equation shows the process of (1)
A displacement
B oxidation
C redox
D reduction
(iv) Copper sulfate solution is the electrolyte used in this electrolysis process.
Explain how copper sulfate solution conducts electricity. (2)
.............................................................................................................................................
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.............................................................................................................................................
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63
Q5. When nitrogen and hydrogen react to form ammonia, the reaction can reach a dynamic equilibrium.
Explain what is meant by a dynamic equilibrium.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. Q6. When nitrogen and hydrogen react to form ammonia, the reaction can reach a dynamic equilibrium.
In industry, the reaction between nitrogen and hydrogen is affected by the conditions used.
(i) The pressure used is 250 atmospheres. Explain how the use of a higher pressure would affect the equilibrium yield of ammonia.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. (ii) The reaction between nitrogen and hydrogen to form ammonia is exothermic. The temperature used is 450°C. Explain how the use of a lower temperature would affect the equilibrium yield of ammonia.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
.............................................................................................................................................. (iii) Even at 450°C, the reaction is very slow. State what is used in industry to overcome this problem.
(1)
.............................................................................................................................................. Q7.(a) In the extraction of tin from tin oxide, tin oxide is heated with carbon.
Complete the sentence by putting a cross ( ) in the box next to your answer. When the tin oxide reacts with carbon to form the products
(1)
A tin is oxidised
B tin oxide is reduced
C carbon is reduced
D carbon dioxide is oxidised
64
(c) Metals are obtained from the Earth's crust by different methods. Some metals are found uncombined but others have to be extracted from their ores by electrolysis or by heating the ore with carbon. Explain, using aluminum, gold and iron as examples, how the method used to obtain the metal is related to its position in the reactivity series and to the cost of the extraction process.
(6)
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65
GROUPS IN THE PERIODIC TABLE
What is the name for group 1 elements?
What is the name for group 7 elements?
What is the name for the group 0 elements?
Give 2 properties of alkali metals
Describe the reactions of lithium, sodium and potassium with water
Describe the pattern in reactivity of the alkali metals
Explain the pattern in reactivity of alkali metals
Give the colour and state of chlorine
Give the colour and state of bromine
Give the colour and state of iodine
Describe the pattern in physical properties of the halogens and use this to predict the
physical properties of astatine
66
Describe the chemical test for chlorine
Describe the reaction of chlorine, bromine and iodine with metals to form metal halides
Describe the relative reactivity of the halogens as shown by their displacement reactions
with halide ions in aqueous solutions.
H Explain why displacement reactions are redox reactions in terms of gain and loss of
electrons, identifying which are oxidised and which are reduced.
Explain the relative reactivity of the halogens
Explain why the noble gases are chemically inert
Explain why the uses of noble gases depend on their inertness, low density and low
flammability.
Describe the pattern in the physical properties of some noble gases and use this pattern
to predict the physical properties of other noble gases.
67
6 MARK QUESTION PRACTICE Chlorine, bromine and iodine are in group 7 of the periodic table. The order of reactivity of
these three elements can be shown by carrying out displacement experiments.
You are provided with
potassium bromide solution
potassium chloride solution
potassium iodide solution
bromine solution
chlorine solution
iodine solution
Describe how these solutions could be used to carry out experiments to show
the order of reactivity of bromine, chlorine and iodine, explaining how the results
would show the order of reactivity. You may use equations if you wish. (6) _____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
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_____________________________________________________________________________________________________
QUESTION PRACTICE
1 Look at the table of data below.
Group 0 density (g/cm3)
helium 0.00018
neon 0.0009
argon 0.0018
krypton 0.0038
Describe the trend in density down the group 0 elements.
___________________________________________________________________________________
________________________________________________________________________________ (1)
68
Estimate the density of xenon, the fifth group 0 element.
_____________________ g/cm3 (1)
2 The elements in group 1 of the periodic table are called the ‘alkali metals’.
a Describe the trend in reactivity down the group of alkali metals.
____________________________________________________________________ (1)
b The alkali metals react with water to produce an alkali and hydrogen gas.
c Complete the balanced equation below for the reaction between sodium and water.
d 2Na(s) + 2H2O(l) ___________(aq) + _______(g) (2)
e Compare and contrast the reactions of lithium and potassium with water.
___________________________________________________________________________________
___________________________________________________________________________________
________________________________________________________________________________ (2)
3 The balanced equation shows the displacement of bromine from sodium bromide solution using chlorine water.
Cl2(aq) + 2NaBr(aq) 2NaCl(aq) + Br2(aq)
a Write an ionic equation for this reaction in the box below. You should include ion charges in your equation and
omit spectator ions. You do not need to include state symbols.
(2)
b Explain why this displacement reaction is an example of a redox reaction.
___________________________________________________________________________________
___________________________________________________________________________________
________________________________________________________________________________ (2)
c Which one of the following pairs of solutions will react together? Tick one box.
A chlorine + sodium chloride
B bromine + potassium iodide
C iodine + lithium bromide
D bromine + sodium chloride (1)
69
QUICK TEST - GROUPS
1. Give the name of group 1 elements………………………………………………………………………………………………………………………..
2. Give the order of reactivity of group 1 elements?.....................................................
3. Give 3 observation when group 1 metal is added to water …………………………………………………………………......
................................................................................................. ................
4. Give the balanced equation for adding sodium, Na to water. …………………………………………………………………….
………………………………………………………………………………………………………………………………………………………………………………………………..
5. Give the name of group 7 elements ……………………………………………………………………………………………………………………..
6. Give the order of reactivity of group 7 elements …………………………………………………………………………………………..
7. Complete the equation:
potassium bromide + chlorine
8. What would you observe in the above reaction and why ………………………………………………………………………………
……………………………………………………………………………………………………………………………………………………………………………………………….
9. Give the name of group 0 elements……………………………………………………………………………………………………………………….
10. Describe and explain the reactivity of group 0 elements…………………………………………………………………………….
………………………………………………………………………………………………………………………………………………………………………………………………..
70
RATES OF REACTION AND ENERGY CHANGES
1. Describe how you would use
the following practical to
determine the rate of reaction
between acid and magnesium
ribbon.
………………………………………………………
………………………………………………………
………………………
………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………
2. What improvement could you make to this practical to collect more accurate results?
………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………
3. In a reaction 50cm3 of gas is produced in 30 seconds, what is the rate of reaction?
4. If you increase temperature the rate of reaction …………………………………… . This is because the
particles have ....
5. If you increase the pressure the rate of reaction ……………………………………… . This is because the
particles …
6. If you increase the surface area (by making the substance a powder) the rate of
reaction………………………………….. This is because…
7. If you increase the concentration the rate of reaction …………………………………….. This is because….
8. A …………………………………… also increases the rate of reaction by ……………………………….
Mass of catalyst (g)
Time (s)
71
What are enzymes and where are they sometimes used?
Describe an exothermic reaction
Describe an endothermic reaction
Explain why some reactions are exothermic
Explain why some reactions are endothermic
Explain the term activation energy
Draw an energy profile diagram of an endothermic reaction. Add the activation energy
and label.
72
Draw an energy profile diagram of an exothermic reaction. Add the activation energy and
label.
QUESTION PRACTICE
Q1 (a) Calcium carbonate reacts with dilute hydrochloric acid. Complete the sentence by putting a cross ( ) in
the box next to your answer. (1)
In this reaction hydrochloric acid is
A precipitated
B displaced
C neutralised
D combusted
(b) The equation for the reaction is
The diagram shows the heat energy contained in the reactants and the heat energy contained in the products.
73
Use the diagram to explain why this reaction is as an exothermic reaction. (2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
(c) If dilute hydrochloric acid is heated before calcium carbonate is added, the rate of reaction increases.
Explain, in terms of particles, why the rate of reaction increases.
(3)
..............................................................................................................................................
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Q2. Zinc is a metal. Zinc reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen. Edward used this apparatus to investigate the speed of the reaction between zinc and dilute hydrochloric acid.
(i) Edward's results for 50 °C are shown on the graph.
Sketch a line on the graph to show the results that Edward should expect to obtain if he carried out the experiment to completion at 30 °C.
(2)
74
(ii) When zinc powder is used, instead of larger pieces of zinc, the reaction is faster. Explain, using ideas about particles, why the reaction is faster when zinc powder is used.
(2) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. (iii) Balance the equation for the reaction of zinc with dilute hydrochloric acid by putting a number in the space provided.
(1) Zn + . . . . . . . . . . . . . HCl → ZnCl2 + H2
(iv) The reaction between zinc and dilute hydrochloric acid is exothermic. Explain, in terms of breaking and forming bonds, why this reaction is exothermic.
(3) .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. Q3. (a) A student investigated the rate of a reaction. The student investigated the reaction between zinc and dilute sulfuric acid. The products are zinc sulfate, ZnSO4, and hydrogen. (i) Write the balanced equation for this reaction.
(2) ..............................................................................................................................................
(b) Zinc is reacted with copper sulfate solution. The equation for the reaction is Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
(i) What type of reaction is this? (1)
Put a cross ( ) in the box next to your answer.
A decomposition
B displacement
C dissolving
D neutralisation (ii) This reaction is exothermic. On the diagram below draw labelled lines to show the relative energies of the reactants and products in this reaction.
(2)
75
4 The gases nitrogen and hydrogen react to form ammonia, as shown in the balanced equation below. The ⇌ sign
shows that this reaction is reversible. In industry the reaction is often carried out in the presence of small pieces of
iron, which act as a catalyst. A catalyst does not alter the products formed in the reaction.
N2(g) + 3H2(g) ⇌ 2NH3(g)
a State the role of a catalyst in a reaction.
_______________________________________________________________________________ (1)
b State why the iron catalyst is in the form of small pieces rather than large lumps.
________________________________________________________________________________ (1)
c This reaction profile represents the energy changes
that occur during the reaction of nitrogen and
hydrogen without a catalyst present.
i On the figure, draw in a dotted line to represent
the reaction profile when a catalyst is used.
(2)
ii Draw an arrow on the figure to show the
activation energy for the reaction without the
catalyst.
(1)
5 The energies of some common bonds are shown in the table below.
Covalent bond C H O H O = O C = O C C C = C
Bond energy (kJ mol−1)
414 458 497 798 346 602
a State what is meant by the energy of a bond.
________________________________________________________________________________ (1)
b Use the bond energies in the table to calculate the energy change (in kJ mol−1) that occurs when ethene is
burned completely in oxygen. The equation for the reaction is shown below.
Answer: ______________________ kJ mol−(3)
76
C2 Key Assessment Task Rates of Reaction (H)
Reactions can occur when particles collide. Rates of reactions can be altered by changing conditions. Explain how the rate of reaction between a solid and a liquid is altered by changing the size of the pieces of solid and by changing the temperature of the liquid. (6)
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Rates of Reaction (F)
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Hydrochloric acid reacts with magnesium metal to produce hydrogen gas.
magnesium + hydrochloric acid → magnesium chloride + hydrogen
Describe how you could use magnesium ribbon and a solution of hydrochloric acid to show
that decreasing the concentration of the hydrochloric acid changes the rate of this reaction.
77
RATES OF REACTION AND ENERGY QUESTIONS Q1. A student used the equipment in Figure 6 to investigate the rate of reaction between zinc and excess dilute hydrochloric acid.
Figure 6
The student uses the following method:
place a known mass of granulated zinc into the conical flask
pour 25 cm3 of dilute hydrochloric acid (an excess) into the conical flask and fit the bung quickly into the neck of the flask
measure the volume of gas produced every 20 seconds until after the reaction finishes.
Figure 7 shows the results.
(a) Give the name of a piece of equipment that can be used to measure 25 cm3 of dilute hydrochloric acid accurately.
___________________________________________________________________________________________(1)
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(b) Draw a graph of the volume of hydrogen gas produced against time using the grid. (3)
(c) The average rate of reaction in the first 20 seconds in cm3 of hydrogen produced per second is (1)
A 2.1
B 8.4
C 21
D 84
(d) The student repeated the experiment keeping all conditions the same but using the same mass of powdered zinc instead of granulated zinc.
On the grid above sketch the graph you would expect when the experiment is repeated using powdered zinc. Label your line A (2)
Q2. During any reaction, reactants are used up and the rate of reaction decreases.
Explain, in terms of particles, why the rate of reaction decreases .(2)
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Q3. The decomposition of hydrogen peroxide is catalysed by adding a small amount of manganese(IV) oxide.
Which of these graphs shows the mass of the catalyst as the reaction takes place? (1)
Q4. What type of chemical change causes a decrease in temperature? (1)
A combustion
B endothermic
C exothermic
D neutralisation Q5. The energies of some bonds are shown in the table.
Hydrogen reacts with chlorine to form hydrogen chloride.
H2(g) + Cl2(g) → 2HCl(g)
Calculate the energy change, in kJ mol–1, for the reaction of 1 mol of hydrogen gas, H2, with 1 mol of chlorine gas, Cl2, to form 2 mol of hydrogen chloride gas, HCl.
(4)
energy change = ........................................................... kJ mol−1
80
Q6. When solid ammonium chloride is shaken with water, a colourless solution forms and the temperature changes from 20°C to 16°C.
Give the name of the type of heat change occurring.
(1)
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Bond C-C C-H C=O C-O O-H O=O
Bond energy
kJmol-1
346 413 740 360 463 497
Q7. Use the bond energies in the table above to calculate the overall energy change of the reaction below.
CH4 + 2O2 CO2 + 2H2O
Q8. Use the bond energies in the table above to calculate the overall energy change of the reaction below.
C2H5OH + 3O2 2 CO2 + 3H2O
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CORE PRACTICAL – RATES OF REACTION (TEMPERATURE)
Section Answer
What is practical about?
What was changed ?
What was measured?
How was it measured?
What was kept the
same?
What equipment was
used to make the
measurements
82
CORE PRACTICAL – RATES OF REACTION (SURFACE AREA)
What is the practical about?
What was changed?
What was measured?
What was kept the same?
What could you use to measure the gas volume more accurately?
If 65cm3 of gas was produced in 75s calculate the average rate of volume of gas produced per second.
83
FUELS AND EARTH SCIENCE
Describe a hydrocarbon
Describe crude oil
Describe how crude oil is separated
Give the names and use of the different fractions
Gases –
Petrol –
Kerosene –
Diesel Oil-
Fuel Oil-
Bitumen-
Give the rhyme to remember the order of the fractions from fractional distillation
Describe how the number of carbon and hydrogen atoms in the molecule changes the
Boiling point-
Viscosity –
Ease of ignition-
Describe an homologous series
What is produced in the complete combustion of a hydrocarbon?
What is produced in the incomplete combustion of a hydrocarbon?
Explain how carbon monoxide behaves as a toxic gas
How does sulphur dioxide get produced from hydrocarbon fuels?
84
How is acid rain caused?
How do oxides of nitrogen get produced?
Give the advantages and disadvantages of using hydrogen rather than petrol as a fuel
Where is methane found?
What does cracking do?
Why is cracking necessary?
How were the gases produced in the Earth’s early atmosphere?
What were the gases in the Earth’s early atmosphere?
How did the oceans form?
Describe 2 ways in which the amount of carbon dioxide in the Early atmosphere
decreased
Describe the chemical test for oxygen
Describe the greenhouse effect and explain how it occurs
What is the evidence for human activity causing climate change?
Describe the potential effects on the climate of increased levels of carbon dioxide and
methane
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QUESTION PRACTICE
1.The modern atmosphere is a mixture of oxygen and other gases.
Which of these is the chemical test for oxygen? Tick one box.
A Limewater turns milky.
B A lighted splint gives a pop.
C A glowing splint relights.
D Damp red litmus paper turns blue. (1)
2. The use of hydrocarbon fuels can cause the production of sulfur dioxide and oxides of nitrogen.
Explain how this sulfur dioxide forms.
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3. Explain how these oxides of nitrogen are produced.
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4. At oil refineries, some crude oil fractions undergo a process called cracking.
Give two reasons why cracking is needed.
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5. Propane is a substance found in crude oil. Its molecular formula is C3H8.
Draw the structure of propane, showing all the covalent bonds.
(1)
Propane is a member of the alkane homologous series of compounds. The next member of this
homologous series is called butane.
Write the molecular formula of butane.
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Explain why the alkanes form a homologous series.
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Incomplete combustion of propane happens in a limited supply of air. Carbon monoxide forms.
i Explain how carbon monoxide behaves as a toxic gas.
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ii Balance this equation for the incomplete combustion of propane.
C3H8 + ___ O2 → C + ___ CO + ___ H2O (1)
iii Write a balanced equation for the complete combustion of propane.
_____________________________________________________________________________ (2)
An international body called the IPCC (Intergovernmental Panel on Climate Change) was set up in 1988.
It is responsible for assessing the science related to climate change. The IPCC publishes reports every few years.
The image shows part of a newspaper article following the third IPCC report.
e Describe how greenhouse gases in the atmosphere keep the Earth warm.
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2. Explain whether the graph provides evidence that an increase in carbon dioxide is causing the Earth’s
temperature to rise.
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f Explain how climate change could lead to increasing sea levels.
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Describe two different ways in which the effects of rising sea levels could be limited.
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________________________________________________________________________________ (2)
6. Crude oil is a complex mixture of hydrocarbons. These hydrocarbons are separated into useful mixtures,
called fractions. Explain how crude oil is separated into fractions.
Name two liquid crude oil fractions and explain how their properties differ, making them suitable for
different uses.
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