chemistry perfect-score-module-form-4-set-1

Set 1 Structure of the atoms & Chemical Equation Perfect Score F4 2010

Chemistry Perfect Score Module Form 4 2010 Set 1

1

STRUCTURE OF THE ATOMS 1. Matter is anything that …………………………………………………. and has …………………….

2. The particle theory of matter state that matter is ……………………………..………………………… 3.

4.

Property Solid Liquid Gas Diagrammatic representation of the particles in each of the physical states

Arrangement of particles.

Forces of attraction between particles

Movement of particles

Energy content

5. Subatomic particles in an atom.

Subatomic particle Symbol Relative mass Charge

6. Isotope are atoms with the same ………………………………………………… but different

………………………………………………………………………………….

7. The isotopes of an element have same ………………………………………….….. but different

………………………………… because they have ….………………………………………………

8. Compare and contrast the atoms below.

Type of particle Example

12 C 6

14 C 6



2

9. Complete the table below.

Isotope Uses

Carbon-14

Cobalt-60

Sodium-24

PAPER 2 : STRUCTURE

1.

(a) Diagram 1.1 shows the results of an experiment to investigate the movement of bromine particles in air.

(i) State the name of the process involved in this experiment.

………………………………………………………………………………………...…...……… [1 mark]

(ii) State the type of particles present in bromine gas.

………………………………………………………………………………………….....……… [1 mark]

(iii) Explain the observation in this experiment based on the kinetic theory of matter.

……………………………………………………………………………………….…...………

……………………………………………………………………………………….…...………

……………………………………………………………………………………….…...………

[3 marks]

Bromine vapour

Reddish brown vapour spreads throughout both gas jars within 10 minutes

Air Gar jar Cover

Cover removed Diagram 1.1



3

(b) Diagram 1.2 shows a graph of temperature against time when solid X is heated? (i) State the melting point of X.

………………………………………………………………………………...…………………

[1 mark] (ii) What happens to the temperature while the substance changes state? Explain.

……………………………….…………………………………………………...…………..……

…………………………………………………………………………………...…………...……

…………………………………………………...………………………………………...………

[2 marks] (iii) Explain the movement of particles X between R and T during heating.

……………………………………………………………………………………………...………

……………………………………………………………………………………………...………

[2 marks]

2. Diagram 2 shows the set-up of apparatus to investigate the reaction between concentrated hydrochloric acid

and concentrated ammonia solution to form substance X. Based on the information, answer the following questions.

(a) (i) What is the observation in the glass tube?

……………………………………………………………………………………...………

[1 mark]

Glass wool soaked in concentrated hydrochloric acid

Time, s

Temperature

Diagram 1.2

Diagram 2

83

Glass wool soaked in concentrated ammonia solution

R T



4

(ii) Name substance X

……………………………..……………………………………………………………...………

[1 mark] (iii) Name the process occurs in the glass tube.

…..………………………………………………………………………………………...………

[1 mark] (b) Which gas diffused faster? Why?

…………………………..…………………………………………………………………...…….……

………….…….………………………………………………………………………………...……….

[2 marks] (c) Write the chemical equation for the reaction in the experiment.

……………………..…………………………………………………………………………...………

[1 mark] 3. Table 3 shows proton number and nucleon number for atom W, X and Y.

Atom Proton number

Nucleon number

W 11 23 X 17 35 Y 17 37

(a) (i) What is meant by proton number?

.....................................................................................………………………………............... [1 mark]

(ii) What is the number of neutron in atom W ?

......................................................................………………………………………................ [1 mark]

(b) Which atoms are isotopes? Explain why. ............................................................................................................................................................ ...........................................................................................................................................................

[2 marks] (c) Write the electron arrangement of atom X .

.......................... ...................................................................................................................................

[1mark]

Table 3



5

(d) (i) Draw the electron arrangement of atom Y. In your diagram , show the number of proton and the number of neutron in the nucleus.

[2 marks]

(ii) What is the number of valence electron of atom Y? .....................................................................................................................................................

[1 mark] (iii) Write the formula of ion Y.

.....................................................................................................................................................

[1 mark]

(e) Write the symbol of atom X in the form of X AZ .

..............................................................................................................................................................

[1 mark]

4. (a) Diagram 4.1 shows the set-up of an experiment to determine the melting point of

solid X.

The temperature of X is recorded at 30 seconds intervals as shown below.

Time/second 0 30 60 90 120 150 180 210

Temperature/oC 70 77 80 80 80 82 85 95

(i) Plot the graph of temperature against time for the heating of X on the graph

paper. [3 marks]

Thermometer

Water

Diagram 4.1



6

Graph temperature against time



7

(ii) On the graph that you have drawn in (a), label the melting point of substance X.

[1 mark]

(iii) Explain why the temperature remains constant from 60 s to 120 s?

…………….……......................................................................................................................

………….................................................................................................................................. [2 marks]

(iv) Draw the arrangement of particles in X at 85oC

[ 1 mark ] (b) Why has the solid X in the boiling tube be stirred constantly with the thermometer during the

experiment? ……………………………....................................................................................................................

[1 mark] (c) Why solid X is not directly heated without using water bath? …………..……………….....................................................................................................................

[1 mark] 5. Table 5 shows four substances and their respective formulae.

Substance Chemical formula Iodine I2

Copper Cu Ethanol C2H5OH

Potassium chloride KCl

(a) State 2 substances that consist of molecules.

……………………………..................................................................................................................... [2 marks]

(b) Which of the following substances has a highest melting point? ……………………...............................................................................................................................

[1 mark] (c) State the substance that can conduct electricity in the solid state.

……………………............................................................................................................................... [1 mark]

(d) Name the particles present in potassium chloride.

……………………............................................................................................................................... [1 mark]

Table 5



8

PAPER 2 : ESSAY

6. Diagram 6.1 shows an atom of an element based on the model by James Chadwick.

(a) Compare the relative mass and the charge of two of the subatomic particles in diagram 6.1.

[4 marks]

Diagram 6.2 shows an atom of element X. (b)

(i) Describe fully the atomic structure shown in diagram 7.2. [4 marks]

(ii) Write a symbol for the element in the form of

[2 marks]

(c) Graph 6.3 shows the heating curve of element Y.

Describe the graph in term of states of matter, particles arrangements and changes in energy. [10 marks]

to t1 t2 t3

Temperature /o C

Time, minutes

Graph 6.3

Electron Proton Neutron

Diagram 6.1

7p 7n

Diagram 6.2

X

A

Z

Melting point



9

7 (a) What is meant by “melting point”? During the melting of naphthalene, the temperature remains constant even though heat is applied. Explain why.

[4 marks]

(b) Describe the change of the kinetic energy, arrangement and the forces of attraction between the particles at the following states:

(i) Before condensation (ii) During condensation

(iii) After condensation [10 marks]

(c) Diagram 7 shows the electron arrangement of ion Y3+.

(i) Calculate the nucleon number of atom Y. [2 marks]

(ii) Y reacts with oxygen to form oxide Y, with the formula Y2O3. The chemical equation for reaction Y with oxygen is show as: 4Y + 3O2 2Y2O3. Given that the relative atomic mass of Y = 27 and O = 16. Calculate the mass of oxide Y, Y2O3 formed when 10.8 g Y is completely burnt in oxygen.

[4 marks] PAPER 3 : STRUCTURE

Condensation is the process where a gas changes to its liquid state at a certain temperature and pressure when it is cooled.

Gas jar cover

Gas jar

Bromine

vapour

Jelly Water Potassium manganate(VII)

A B C Diagram 8

14 n

e

e

e e

e e

e e

e e 3+

n neutron e electron

Diagram 7



10

8. A group of students set up the apparatus for an experiment as shown in diagram 8. The result is obtained by

the students are shown in table 8.

Experiment Observation A After a few minutes the gar jar was filled with a reddish brown gas. B After a few hours, the water turns purple. C After a few days, the jelly turns purple.

(a) State the aim of the experiments carried out. ……………………................................................................................................................................ (b) State the hypothesis of the experiments. ……………………............................................................................................................................... ……………………............................................................................................................................... (c) State (i) The manipulated variable. ……………………..................................................................................................................... (ii) The responding variable. ……………………..................................................................................................................... (iii) The fixed variable of the experiments. ……………………..................................................................................................................... (d) Based on the observation, arrange the three states of mater in a sequence to show their speed in increasing order. …………………….............................................................................................................................. (e) Based on the rate of the movement of the particles, describe the arrangement of the particles in the

three states of matter. …………………….............................................................................................................................. …………………….............................................................................................................................. …………………….............................................................................................................................. (f) Give the daily application of the process in one of the above experiment. ……………………..............................................................................................................................



11

CHEMICAL FORMULA AND EQUATION 1. Write the chemical formula of the compound in the table below.

Ion Chloride Nitrate Hydroxide Sulphate Carbonate oxide

Sodium

Magnesium

Lead(II)

Copper (II)

Iron (II)

Iron (III)

Aluminium

2. Write balanced chemical equation for the following chemical reactions.

(a) Heat solid of copper (II) carbonate ………………………………………………………………………………………….

(b) Nitric acid reacts with sodium hydroxide

…………………………………………………………………………………………. (c) Hydrochloric acid reacts with zinc metal

………………………………………………………………………………………….

(d) Copper(II)nitrate reacts with magnesium

…………………………………………………………………………………………. (e) Chlorine gas reacts with lithium hydroxide

………………………………………………………………………………………….

(f) Hydrogen gas reacts with lead(II) oxide

………………………………………………………………………………………….

3. Avogadro constant, NA is defined as the number of particles in one mole of a substance [1 Mol any substance consist of 6.02 X 1023 particles]. Calculate the number of particles in: (a) 0.1 mol of calcium

(b) 1.5 mol of iron

(c) 2.0 mol of oxygen gas

(d) 1.5 mol of helium

(e) 2.0 mol hydrogen chloride



12

4. Calculate the number of moles of the following substances. (a) 6.0 x 1023 aluminium

(b) 1.8 x 1021 argon

(c) 1.2 x 1023 bromine gas

(d) 2.4 x 1020 carbon dioxide

(e) 3.0 x 1023 ammonia

5. Calculate the mass of following substances.

a) 1.5 mol of chlorine gas

b) 2.5 moles of oxygen gas

c) 2.0 moles of sulphuric acid

d) 0.5 moles of ammonia, NH3

e) 2.5 moles of lead (II) carbonate f) 0.5 moles copper(II) nitrate, Cu(NO3)2

Molar volume: The volume of one mole of the gas [22.4 dm3 mol-1 at STP, standard temperature and pressure] [24 dm3 mol-1 at Room condition]

6. Calculate the volume of gases below.

(a) 0.5 mol of chlorine at STP.

(b) 0.2 mol of carbon dioxide at Room condition.

(c) 1.5 mol of methane at room condition.

(d) 0.5 mol of helium at room condition.

(e) 2.5 mol of ammonia at STP



13

7. Calculate the number of moles of the gases below.

(a) 250 cm3 of carbon dioxide in room temperature.

(b) 500 cm3 of hydrogen sulfide at STP.

(c) 200 cm3 of hydrogen chloride in room temperature.

(d) 750 cm3 of neon in room temperature.

(e) 300 cm3of ammonia at STP.

8. Magnesium powder reacts with hydrochloric acid to produce salt and hydrogen gas. (a) Write the balance chemical equation for this reaction.

………………………………………………………………………………………….

(b) If 2.4 g of magnesium powder is added into excess hydrochloric acid, calculate, (i) The mass of salt formed.

(ii) The volume of hydrogen gas liberated at room temperature. 9. Lead is extracted according to the following equation.

C + PbO CO2 + Pb

(a) Write the balanced chemical equation for the reaction.

(b) Determine the number of moles of lead extracted from 0.5 mole of lead (II) oxide.

(c) Calculate the number of moles of carbon required to extracts 0.5 mole of lead(II) oxide.

(d) What is the mass of lead are produced if 44.6 g of lead (II) oxide is heated with excess carbon. [ RAM : Pb = 207, O = 16, C = 12 ]



14

10. Excess sodium carbonates is added into 50 cm3 of 0.5 mol dm-3 copper(II) chloride.

The chemical equation for the reaction is as follows:

CuCl2 + Na2CO3 NaCl + CuCO3

(a) Balance the chemical equation for the reaction.

(b) Calculate the mass of copper(II)carbonate.

11. 5g of calcium carbonate is added to excess hydrochloric acid. (a) Write balanced chemical equation for the reaction.

……………………………………………………………………………………….……. (b) Determine the volume of carbon dioxide gas evolved at room temperature

12. When sodium bicarbonate is heated, it decomposed to sodium carbonate, carbon dioxide and water. (a) Write a balanced chemical equation for the decomposition of sodium bicarbonate on heating.

……………………………………………………………………………………………..….

(b) If 8.4 g of sodium bicarbonate decomposes, calculate (i) The volume of carbon dioxide gas evolved at room temperature.

(ii) The mass of sodium carbonate formed.



15

Concentration of acids and alkalis (STOICHEIOMETRY)

The concentration of a solution is the mass (in gram) or the number of mole of solute dissolved in a solvent to form 1.00 dm3 of solution.

Concentration, g dm-3 Mass of solute, g Volume of solution , dm3

Concentration, mol dm-3 / molarity

Number of mole of solute, mol Volume of solution , dm3

Ma = Concentration of the acid, Mb = Concentration of the alkali Va = Volume of used acid, Vb = Volume of used alkali a = the number of mole of acid, b = the number of mole of alkali 13. 100cm3 of HCl 2.0 mol dm-3 reacts completely with excessive zinc powder. Calculate the

volume of gas released at room temperature? (Molar volume = 24 dm3 at room temperature).

14. 5 g of Calcium carbonates dissolves in 100 cm3 of nitric acid 0.5 mol dm-3 to produce salt,

carbon dioxide gas and water. (i) Write out the equation.

………………………………………………………………………………………..…… (ii) Calculate the moles of calcium carbonates used. (RAM Ca =40, C = 12, O = 16).

(iii) Calculate the moles of acid.

(iv) Calculate the volume of gas produced.

Titration Formula MaV2 = a MbVb b

Dilution M1V1 = M2V2



16

15. X g sodium carbonate reacts completely with 100 cm3 hydrochloric acid

1.0 moldm-3 to produce sodium chloride, carbon dioxide and water. Find X. (relative atomic mass: Na =23, C = 12, O = 16)

16. 10 g of copper(II) oxide reacts completely with 100 cm3 hydrochloric acid to form copper(II) chloride and water. Calculate the molarity of acid used. (JAR Cu =64, O = 16 )

17. The concentration of sodium hydroxide solution is 8.0 g dm-3.

(a) What is the molarity of the solution?

(b) What is the molarity of the solution produced when 100 cm3 of distilled water is added to 50 cm3 of this solution?

18. In the titration experiment, 25.0 cm3 of 2.0 mol dm-3 sodium hydroxide solution is titrated with sulphuric

acid from a burette. 18.50 cm3 of sulphuric acid is needed for complete neutralization. (a) Write a balanced chemical equation for the neutralization.

…………………………………………………………………………………………………

(b) Calculate the number of mole of sodium hydroxide used in this experiment.

(c) Calculate the number of moles of sulfphuric acid needed to exactly neutralize 25.0 cm3 of 2.0 mol dm-

3sodium hydroxide.

(d) Calculate the molarity of sulphuric acid.

19. 1.25 mol dm-3 hydrochloric acid reacts completely with 25.0 cm3 of 1.0 mol dm-3 sodium carbonate.

(a) Write a balanced chemical equation for this reaction.

……………………………………………………………………………………………………

(b) Calculate the number of mole of sodium carbonate used in this experiment.

(c) Calculate the volume of hydrochloric acid needed to exactly neutralize 25.0 cm3 of 1.0 mol dm-3 sodium carbonate.



17

PAPER 2: STRUCTURE

1. Diagram 1 shows the set-up of the apparatus for an experiment to determine the empirical formula of an oxide of copper.

Table 1 shows the results of an experiment after heating, cooling and weighing are repeated until a constant weight is obtained.

Substance Mass(g)

Mass of combustion tube + porcelain dish 18.75 g Mass of combustion tube + porcelain dish + oxide of copper 20.75 g Mass of combustion tube + porcelain dish + copper 20.35 g

(a) What is meant by empirical formula? ………..………………………………………………………………………………………….

[1 mark] (b) Based on Table 5 results,

(i) Calculate the mass of copper and the mass of oxygen used in the experiment.

[2 marks]

(ii) Calculate the mole ratio of copper atoms to oxygen atoms. Given that the relative atomic mass of Cu, 64; O ,16.

[2 marks] (iii) State the empirical formula of this oxide of copper.

……….………………………………………………………………………………………

[1 mark] (iv) Write the chemical equation for the reaction in this experiment.

……………...………………………………………………………………………………

[1 mark]

Oxide of copper

Dry hydrogen gas

Heat

Diagram 1

Table 1



18

(c) Describe the steps that should be taken to ensure that all the air in the combustion

tube has been expelled , before any heating is carried out. …………………………..…………………………………………..………………………… . ……………………………….……………………………………………………………… ……………………………………...…………………………………………………………

[3 marks] 2. (a) Culculate the relative molecular or formula masses of the following substances.

(i) Ethanol, C2H5OH. Given that relative atomic mass of H = 1, C = 12, O = 16.

[1 mark]

(ii) Zinc nitrate, Zn(NO3)2 Given that relative atomic mass of O = 16 , N = 14, Zn = 65 .

[1 mark] (b) A closed glass bottle contains 4 mol molecules of oxygen, O2.

(i) What is the number of oxygen molecules in the bottle?

[1 mark] (ii) How many oxygen atoms are there in the bottle?

[1 mark]

(c) Find the number of moles of atoms in a sample containing 9.03 × 1020 atoms of copper.

[1 mark] (d) Calculate the mass, in gram, of 3.5 moles of copper(II) carbonate, CuCO3.

Given that relative formula mass of CuCO3 = 124

[1 mark]

(e) When silver carbonate, Ag2CO3 is heated, it will decompose to produce silver metal, carbon dioxide gas and oxygen gas as shown in the equation below.

2Ag2CO3(s) 4Ag(s) + 2CO2(g) + O2(g)



19

A student heats 8.28 g silver carbonate. Calculate the volume of carbon dioxide gas, CO2 collected at room temperature. Given that relative atomic mass of C = 12, O =16, Ag = 108,

[3 marks]

3. Diagram 3 shows 3.1 g of copper (II) carbonate being heated strongly in attest tube. The gas given out is passed into limewater in a test tube through a delivery tube.

(a) State the observation made when copper(II)carbonate powder is heated until the reaction is complete.

…………………………………………………………………………………………………

[1 mark] (b) Write the chemical equation to represent the reaction that takes place. ……………………………………………….…………………………………………………

[1 mark] (c) Calculate the number of moles of copper(II)oxide produced.

[2 marks] (d) Calculate the volume of gas produced at STP.

[2 marks] (e) (i) What can be observed if the product is heated in a stream of hydrogen gas?

..………………………………………………………………………………………

[1 mark] (ii) Calculate the mass of the substance produced.

[2 marks]

Copper(II) carbonate

Heat strongly

Lime water

Diagram 3



20

PAPER 2 : ESSAY 4.

(a) The information below is regarding substance X

(i) Determine the empirical formula of substance X. [Given that the relative atomic mass of C = 12 , H = 1]

(ii) Determine the molecular formula of substance X. (iii) Based on the answers in (a)(i) and (a)(ii) , compare and contrast the empirical formula and the molecular formula.

[ 8 marks]

(b) Magnesium can react actively with oxygen to form magnesium oxide. Describe an activity that can be carried out in the laboratory to determine the empirical formula of magnesium oxide. Include the calculations involved in your answer. Given that the relative atomic mass for O = 16, Mg = 24.

[11 marks]

Carbon 85.70% Hydrogen 14.30% Relative molecular mass = 56



21

PAPER 3 : STRUCTURE 5. A student carried out an experiment to determine the empirical formula of magnesium oxide.

The steps and set-up of apparatus of the experiment are shown in Diagram 5.

1. The crucible and lid are weighed.

2. The crucible, lid and magnesium powder are weighed.

3. The magnesium powder is heated until it reacts completely with oxygen.

4. The crucible, lid and magnesium oxide are weighed when cooled.

Diagram 5

Magnesium powder

crucible

lid

digital balance

white fumes

magnesium oxide powder

heat

123.3632g

128.1580g

131.3580g



22

(a) Complete the following table by stating the observations and related inferences in the experiment.

Observations Inferences (i) ................................................ ....................................................

(i) ................................................................ ....................................................................

(ii) ............................................... ....................................................

(ii) ............................................................... .....................................................................

(iii) ) .................................................... ....................................................

(iii) .................... ............................................... ....................................................................

[6 marks]

(b) Round off the reading to two decimal places and record it in the table below.

(c) (i) Calculate the mass of magnesium that has been used. (ii) Calculate the mass of oxygen which reacted with magnesium. (iii) Determine the empirical formula of magnesium oxide. Use the information that the relative atomic mass, O = 16, Mg = 24

(d) The student wants to determine the empirical formula of lead(II) oxide. He used the steps and set-up

of apparatus as the experiment before. Predict whether the empirical formula of lead(II) oxide can be determined. Explain your answer.

...............................................................................................................................................................

Description Mass / g The crucible and lid.

The crucible, lid and magnesium powder.

The crucible, lid and magenesium oxide.

chemistry perfect-score-module-form-4-set-1

Education