Lim Ting Jie

VS Class of 2011

Quick References

Website Chemistry

The Republished

2012 Edition

SECTION I: EXPERIMENTAL CHEMISTRY

1. Experimental Chemistry

1.1: Experimental design

(a) name appropriate apparatus for the measurement of time, temperature, mass and volume, including burettes, pipettes, measuring cylinders and gas syringes

Time/s Temperature/K or oC Mass/g Volume/cm3

Stopwatch Mercury thermometer (for laboratory readings -10 to 110oC) Temperature sensor & Datalogger (for more accurate readings)

Beam balance Electronic balance (for more accurate readings)

Beaker (fixed) Measuring cylinder (‡ 1 cm3) Pipette (‡ 0.1 cm3) Burette (fixed, 0.1 cm3)

(b) suggest suitable apparatus, given relevant information, for a variety of simple experiments, including collection of gases and measurement of rates of reaction

Collection of gases.

Insoluble gases Soluble gases Density of gases

Hydrogen

Carbon dioxide (slightly soluble)

Oxygen (very slightly soluble)

Ammonia

Chlorine

Hydrogen chloride

Sulfur dioxide

Gases less dense than air have molecular masses below 30

Gases denser than air have molecular masses above 30

Drying of gases.

Most gases except ammonia Hydrogen gas Ammonia gas

conc. H2SO4 CaCl2

CaO

1.2: Methods of purification and analysis

(a) describe methods of separations and purification for the components of the following types of mixtures: (i) solid-solid (ii) solid-liquid (iii) liquid-liquid (miscible and immiscible)

Point Sub Points What Content How Content Key Words

Solid-solid

Filtration Soluble solid from insoluble solid

Similar method to precipitation

1. one insoluble in water 2. other insoluble

Sublimation Solid that is able to sublime from solid that is unable to decompose when heated

Inverted funnel with a wet cloth on the sides over the heated evaporating dish

1. one able to sublime 2. the other unable to

decompose 3. inverted funnel 4. wet cloth 5. evaporating dish

Solid-liquid

Simple Distillation Solid from the liquid that it has dissolved in to obtain the liquid as it has a lower boiling point

Draw. The liquid will boil to become a gas and pass through the Liebig condenser to be condensed and collected as liquid in the beaker

1. solid dissolved in liquid 2. obtain liquid 3. boiling chips 4. liebig condenser 5. thermometer 6. beaker 7. round bottomed flask

Evaporation to dryness

Solid which does not decompose on heating from the liquid it has dissolved in to obtain solid

Heat the solution in an evaporating dish over Bunsen burner

1. solid dissolved in liquid 2. obtain solid 3. solid does not decompose 4. evaporating dish

Crystallisation Solid from water that it has dissolved in to obtain the solid crystals

Heat the solution until a hot saturated solution is formed, then allow solution to cool to room temp.

1. solid from water 2. obtain the solid crystals 3. hot saturated solution 4. allow to cool

Liquid-liquid

Simple Distillation Liquids of differing boiling points

As above 1. differing boiling points

Fractional distillation

Liquids of differing boiling points that are misible

As above, but with fractionating column

1. differing boiling points 2. misible 3. fractionating column

Separating funnel Immisible liquids of differing densities

Include two beakers in the experiment

1. differing densities 2. beakers

Paper chromatography

Liquids of differing solubilities

Paper soaks up, more soluble in solvent carried further away

1. differing solubilities

(b) describe paper chromatography and interpret chromatograms including comparison with ‘known’ samples and the use of Rf values

Point Content

Rf value Ratio of distance travelled by the substance to the distance travelled by solvent (front)

(c) explain the need to use locating agents in the chromatography of colourless compounds

Point Content

Use of locating agents To make colourless compounds visible so that their Rf value can be taken

(d) deduce from the given melting point and boiling point the identities of substances and their purity

Point Content

Effects of impurities

Decrease melting point

Increase boiling point

Changes state over a range of temperatures

1.3: Identification of ions and gases

(c) describe tests to identify the following gases

Points How Content What Content

Ammonia Bring the gas over damp red litmus paper Litmus paper turns blue

Carbon dioxide Bubble the gas through limewater A white precipitate will form in it

Chlorine Bring the gas over damp blue litmus paper Litmus paper turns red then bleached

Sulfur dioxide using acidified Potassium Dichromate(VI)

Turns from orange to colourless

SECTION II: ATOMIC STRUCTURE AND STOICHIOMETRY

2: The Particulate Nature of Matter

2.2: Atomic structure

(c) define proton (atomic) number and nucleon (mass) number

Point Content Mem Key words

Proton number The number of positively charged protons in an atom PA positively charged

Nucleon number The total number of protons and neutrons in an atom MN total number

(e) define the term isotopes

Point Content Mem Key words

Isotopes Atoms of the same element with the same number of protons but a different number of neutrons

No. of protons = no. of electrons

1. atoms 2. same element

2.3: Structure and properties of materials

(a) describe the differences between elements, compounds and mixtures

Element Atom Molecule Compound Mixture

Constituents One type of atom Smallest particle of an element

2 or more atoms

2 or more different elements

2 or more substances

Bonding - - Covalently bonded

Chemically combined Physically combined

Purity Pure substance Can still keep the chemical properties of that element

Pure substance

Pure substance -

Ratio - - - Fixed -

(d) deduce the physical and chemical properties of substances from their structures and bonding and vice versa

Point of comparison Giant ionic Simple covalent Diamond Graphite Giant metallic

Boiling and melting points High Low High High High

State in rtp Solid Liquid Or Gas Solid Solid Solid

Organic solvent solubility No Yes No No No

Electrical conductivity (molten)

Yes Generally No No Yes Yes

Electrical conductivity (solid) No Generally No No Yes Yes

Hardness Hard but brittle

N.A. Hard but brittle

Soft Hard and mallaeble

2.4: Ionic bonding

(a) describe the formation of ions by electron loss or gain in order to obtain the electronic configuration of a noble gas

Point Content

Oxidation and reduction

Atoms become ions by losing electrons through oxidation or gaining electrons through reduction in order to obtain an octet structure and become electronically stable.

(b) describe the formation of ionic bonds between metals and non-metals, e.g. NaCl; MgCl2

Formation of cations Formation of anions Formation of ionic bonds

A metal atom loses its valence electrons to form positively charged metal cation

A non-metal atom gains these electrons from the metal atom to form a negatively charged anion

The cations and anions have opposite charged and are attracted to one another by electrosatic attraction to form ionic bonds, holding the atoms of the ionic compound together

2.5: Covalent bonding (a) describe the formation of a covalent bond by the sharing of a pair of electrons in order to gain the electronic configuration of a noble gas

Atoms of non-metals share their electrons to form an octet structure through covalent bonds, reacting with one another in the process.

A covalent bond is the bond that is formed between atoms that share electrons.

2.6: Metallic bonding (a) describe metals as a lattice of positive ions in a ‘sea of electrons’

Point Definition

Metallic bond Force of attraction between positive metal ions and the ‘sea of delocalised electrons’

3. Formulae, Stoichiometry and the Mole Concept

(e) construct chemical equations, with state symbols, including ionic equations

Step Sequence

1 Write out the balanced equation, usually starting with the complex parts

2 Put in state symbols, with water-soluble compounds as aqueous

3 Write out free ions in the aqueuous solutions from their compounds

4 Cancel away spectator ions present on both sides of the equation

5 Write down the uncancelled formulas, with atoms and charges balanced

(f) define relative atomic mass, Ar (g) define relative molecular mass, Mr, and calculate relative molecular mass (and relative formula mass) as the sum of relative atomic masses (h) calculate the percentage mass of an element in a compound when given appropriate information

Point Symbol Definition

Relative atomic mass

Ar The number of times the mass of one atom of an element is greater than 1/12 of the mass of one carbon-12 atom

Relative molecular mass

Mr The mass of a molecule compared to 1/12 the mass of one carbon-12 atom (the relative atomic masses of all the atoms of the molecule)

(j) calculate stoichiometric reacting masses and volumes of gases (one mole of gas occupies 24 dm at room temperature and pressure); calculations involving the idea of limiting reactants may be set

Moles

Mass (g) Particles

Gas volume at r.t.p.

Mr 6 x 1023 24 dm3 / 24000 cm3

Moles Reactants Products

Equation Zn 2 HCl H2 ZnCl2

Before reaction 3 4 0 0

During reaction 2 4 2 2

After reaction 1 0 2 2

(i) calculate empirical and molecular formulae from relevant data

Element C H O Remarks

Percentage in compound (%) 39.1 8.7 52.2 By mass

Relative atomic mass 12 1 16 Use periodic table

Moles 3.26 8.70 3.26 Divide mass by Ar

Molar ratio 1 2.67 1 Divide by the smallest no. of moles

Simplest ratio 3 8 3 Multiply until constant k gives a 1 digit no.

SECTION III: CHEMISTRY OF REACTIONS

4. Electrolysis

(h) describe the electrolysis of aqueous copper(II) sulfate with copper electrodes as a means of purifying copper

Point What Content Usage Examples Ions conc

Inert electrode

Electrodes that do not take part in chemical reactions during electrolysis

Electrodes more reactive than the metal of the electrolyte will undergo a displacement reaction

Carbon, Graphite and Platinum

Decreases (Electrolyte conc decreases when in hydroxide discharge

Reactive electrode

Electrodes which take part in chemical reactions during electrolysis

Purification of a metal of low reactivity like using copper electrodes with copper solution

Metals also included in electrolyte

Remains the same

5: Energy from Chemicals

(b) represent energy changes by energy profile diagrams, including reaction enthalpy changes and activation energies (see 6.1(c),6.1(d))

6. Chemical Reactions

6.1: Speed of reaction

(d) state that some compounds act as catalysts in a range of industrial processes and that enzymes are biological catalysts (see 5(b), 6.1(c) and 10(d))

Catalysts in general Enzymes

Increase in temperature will result in increase of rate of reaction.

Increase in temperature will result in increase of rate of reaction.

But too low a temperature will cause itself to be inactive

Too high a temperature will cause itself to be denatured

May not be made of proteins Made of proteins

May not be specific in their actions Specific in their actions

6.2: Redox

(d) describe the use of aqueous potassium iodide and acidified potassium dichromate(VI) intesting for oxidising and reducing agents from the resulting colour changes

Oxidising agent Reducing agent

Acidified potassium manganate (VI) Acidified potassium dichromate

(VII)

Pale green Aqueous Iron (II) solution

Purple to pale yellow (due to presence of oxidising agent)

Orange to green

Sulfur dioxide gas Purple to colourless Orange to green

Hydrogen peroxide Purple to colourless, effervescence

seen Orange to green, effervescence

seen

Aqueous Sulphite solution Purple to colourless Orange to green

Aqueous Chloride solution

Purple to colourless, a choking yellowish-green gas changes moist

blue litmus paper to red then bleached

Orange to green, a choking yellowish-green gas changes moist

blue litmus paper to red then bleached.

Ea Reactants

Products ∆H = -ve

Ene

rgy/

kJ

Progress of reaction

7. Acids, Bases and Salts

7.1: Acids and bases

(a) describe the meanings of the terms acid and alkali in terms of the ions they produce in aqueous solution and their effects on Universal Indicator

Point Description

Acids Substances that react with water to produce hydrogen ions as the only positive ions

Bases Metal oxides or Metal hydroxides

Alkalis Soluble bases that react with water to produce hydroxide ions

(b) describe how to test hydrogen ion concentration and hence relative acidity using Universal Indicator and the pH scale

Measurement Hydrogen ion concentration test Relative acidity

Universal Indicator

Mixture of dyes that show red in high hydrogen ion concentrations and violet in high hydroxide ion concentration

At high hydrogen ion concentration, relative acidity will be high

pH probe or pH meter

Gives a reading from pH scale of pH value between 0 to 14. The lower the pH value, the higher the hydrogen ion concentration

(d) describe the characteristic properties of acids as in reactions with metals, bases and carbonates

(e) state the uses of sulfuric acid in the manufacture of detergents and fertilisers; and as a battery acid (j) classify sulfur dioxide as an acidic oxide and state its uses as a bleach, in the manufacture of wood pulp for paper and as a food preservative (by killing bacteria)

Sulfuric acid Sulfur dioxide

Manufacture of detergents Bleaching agent

Battery acid in cars Food preservative by killing bacteria

Manufacture of ferilisers Manufacture of wood pulp for paper

(h) describe the characteristic properties of bases in reactions with acids and with ammonium salts

7.2: Salts

(a) describe the techniques used in the preparation, separation and purification of salts as examples of some of the techniques

Reactants Products

Acid + Metal above hydrogen in reactivity series Hydrogen + Salt

Acid + Carbonate Carbon dioxide + Salt + Water

Acid + Base Salt + Water

Reactants Products

Base + Ammonium salt Ammonia gas + Water + Salt

Acid + Base Salt + Water

Conditions ‘ABCM’ Titration Precipitation

Salt Product

Soluble Yes Yes No

Ammonium Grp I No

Prepa-ration

Preparation Acid and Excess insoluble reactant

Acid and Exact souble reactant

Two aqueous solns

Gas and aq. soln

Sepa-ration

Combine and filter Obtain filtrate Obtain filtrate Obtain residue

Purifi-cation

Heat and cool Yes Yes No

Wash and dry With cool water With much water

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(b) describe the general rules of solubility for common salts to include nitrates, chlorides (including silver and lead), sulfates (including barium, calcium and lead), carbonates, hydroxides, Group I cations and ammonium salts

By elimination: If the first step is not fufilled, go on until you reach step 3.

Step 1: Definite solubility Step 2: Solubility w/ exceptions Step 3: Not soluble

Alkali metals Nitrates Ammonium

Sulfates Halides Oxides Hydroxides Barium Calcium

Carbonates Hydrogen

Barium Calcium Lead (II)

Silver Lead (II)

Barium hydroxide Calcium hydroxide Hydrogen carbonate

7.3 Ammonia

(a) describe the use of nitrogen, from (fractional distillation of liquid) air, and hydrogen, from cracking oil (petroleum fractions), in the manufacture of ammonia

(c) describe the essential conditions for the manufacture of ammonia by the Haber process

Point Conditions Ideal

Temperature Low enough to prevent decomposition of ammonia

High enough to ensure a faster rate of reaction 450oC

Pressure Low enough to ensure low operating costs

High enough to prevent decomposition of ammonia

250 atm

Finely divided iron

Catalyst by lowering activation energy required to increase rate of reaction. Finely divided to increase surface area to volume ratio of iron atoms, increasing rate of reaction.

Fine

(d) describe the displacement of ammonia from its salts

Point Content

Displacement Ammonium salt + Alkali + Heat Ammonia gas + Water + Salt

SECTION IV: PERIODICITY

8. The Periodic Table

8.2: Group properties

(c) describe the elements in Group 0 (the noble gases) as a collection of monatomic elements that are chemically unreactive and hence important in providing an inert atmosphere, e.g. argon and neon in light bulbs; helium in balloons; argon in the manufacture of steel

Noble gas Functions

Helium Fill weather balloons (as it is non-flammable)

Neon Advertisement lights

Argon Fill light bulbs (as it does not oxidise the filament)

Krpton Lasik surgery

Xenon Car headlights

(d) describe the lack of reactivity of the noble gases in terms of their electronic structures

Noble gases already have full outershell electrons with a stable electronic configuration. It is hence unreactive. Any gain or loss or sharing of electrons will cause it to lose electronic stability.

9. Metals

9.1: Properties of metals

(b) describe alloys as a mixture of a metal with another element, e.g. brass; stainless steel

An alloy is a mixture of a metal with another element.

Alloy Constituent metals Uses

Brass Copper (70%) and Zinc (30%) Electrical wires

Bronze Copper (90%) and Tin (10%) Medals

Stainless steel 73% Iron, 8% Nickel, 18% Chromium and 1% Carbon Cultery (corrosion resistant)

9.2: Reactivity series (a) place in order of reactivity calcium, copper, (hydrogen), iron, lead, magnesium, potassium, silver, sodium and zinc by reference to (i) the reactions, if any, of the metals with water, steam and dilute hydrochloric acid, (ii) the reduction, if any, of their oxides by carbon and/or by hydrogen

Reaction Abbreviation Way to remember Metal range

Metal + Acid Hydrogen + Salt PL Patrol Leader K to Pb

Metal + Water Hydrogen + Metal Hydroxide PM Prime Minister K to Mg

Metal + Steam Hydrogen + Metal Oxide PI ∏, The Globe K to Fe

Reaction Abbreviation Way to remember Metal range

Metal Oxide + Carbon Metal + Carbon dioxide ZS Zoo Safari Zn to Ag

Metal Oxide + Hydrogen Metal + Steam IS hIS Fe to Ag

K P

Na S PM

Ca C

Mg M PL PI

Al A Carbon

Zn Z

Fe I

Sn T

Pb L ZS Hydrogen

Cu C IS

Hg M

Ag S

(b) describe the reactivity series as related to the tendency of a metal to form its positive ion, illustrated by its reaction with (i) the aqueous ions of the other listed metals (ii) the oxides of the other listed metals

The more reactive metal is able to displace the less reactive metal from its (i) aqueous salt solution or (ii) oxide in the reaction.

Special Cases: K, Na, Ca and Mg can react with water. Hence this reaction between the metal and water will predominate the displacement reaction, occurring first instead. For example, for the reaction between Na (s) and CuSO4 (aq), 2 Na + 2 H2O 2 NaOH + H2 occurring 1st. Thereafter, precipitation reaction occurs. 2 NaOH + CuSO4 Na2SO4 + Cu(OH)2.

(d) describe the action of heat on the carbonates of the listed metals and relate thermal stability to the reactivity series

Reaction Abbr Way to remember Metal range

Metal Carbonate, heated Metal Oxide + CO2 CC Community Club Ca to Cu

Metal Hydroxide, heated Metal Oxide + Steam CC Community Club Ca to Cu

Metal Oxide, heated Metal + Oxygen MP Member of Parliament Hg to Pt

9.5: Iron

(a) describe and explain the essential reactions in the extraction of iron using haematite, limestone and coke in the blast furnace

Step Description Equation

Preparation Stage

Coke [C], Haematite [Fe2O3 with impurities like sand] and Limestone [CaCO3] are added at the top of the blast furnace.

Blasts of hot air blown in from the base through pipes.

C + Fe2O3 +

CaCO3 + SiO2

Coke Burning Exothermic reaction C + O2 CO2

CO Formation Endothermic reaction C + CO2 2 CO

Iron Ore Reduction

CO & CO2 escape through the top, burnt to provide heat for new blasts of hot air. Iron (l) containing carbon flows to the bottom.

Fe2O3 + CO Fe (l) + 3 CO2

Limestone Decomposition

Limestone is heated and decomposed to CO2 and basic oxide CaO, which will react with acidic oxide SiO2 later.

CaCO3 CO2 + CaO

Impurities Removal

Slag (l) floats on top of Iron (l). Both tapped off separately.

Slag mainly used for paving roads SiO2 + CaO CaSiO3 (l slag)

(b) describe steels as alloys which are a mixture of iron with carbon or other metals and how controlled use of these additives changes the properties of the iron, e.g. high carbon steels are strong but brittle whereas low carbon steels are softer and more easily shaped (c) state the uses of mild steel, e.g. car bodies; machinery, and stainless steel, e.g. chemical plants; cutlery; surgical instruments

Point High Carbon Steel Mild (Low Carbon) Steel Stainless Steel

Composition 0.45% C + Fe 0.25% C + Fe 1% C + Fe + Ni + Cr

Properties Strong but brittle Less strong and malleable Corrosion resistant

Uses Hammers Car bodies Industrial Pipes

Cutting Tools Machinery Surgical Instruments

(d) describe the essential conditions for the corrosion (rusting) of iron as the presence of oxygen and water

Rusting Rust Conditions Catalysts

Slow oxidation of iron into hydrated iron (III) oxide, Fe2O3·xH2O

A brittle reddish brown solid

Presence of:

Oxygen

Water

NaCl Common salt

SO2

CO2 Acidic pollutants

SECTION V: ATMOSPHERE

10. Air

(a) describe the volume composition of gases present in dry air

Point Content

Nitrogen approx 79%

Oxygen 20%

Carbon dioxide 0.03%

Argon 0.9%

Helium and Neon 0.002%

Water vapour Varying amounts below 5%

SECTION VI: ORGANIC CHEMISTRY

11: Organic Chemistry

11.1: Fuels and crude oil

(b) describe petroleum as a mixture of hydrocarbons and its separation into useful fractions by fractional distillation

How Fraction Remember Condensation

Petroleum is heated to 360oC in a furnace, evaporating in vapour

Liquified petroleum Long Light fractions have lower boiling points, collected at the top

Petrol Pea

Naptha Nuts.

Kerosene Kick Heavy fractions, higher boiling points, collected bottom

Diesel oil Dogs

Lubricating oil Laugh at

Bitumen Bulldog. Collected as residue

(c) name the following fractions and state their uses

Fraction Uses

Liquified petroleum Cooking, Heating

Petrol Motorcar engines

Kerosene Jet engines, Oil stoves, lamps

Diesel oil Diesel engines

Lubricating oil Lubricants, Waxes, Polishes

Bitumen Road surface paving

(d) state that the naphtha fraction from crude oil is the main source of hydrocarbons used as the feedstock for the

production of a wide range of organic compounds

Fraction Uses

Naptha Raw material (chemical feedstock) for chemical industries (e.g. detergents, medicines)

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11.2: Alkanes

(b) describe the alkanes as an homologous series of saturated hydrocarbons with the general formula CnH2n+2

Point Content

Homologous series Family of organic compounds with similar chemical properties with a regular pattern

Saturated Hydrocarbons containing only single C-C covalent bonds

General formula CnH2n+2 with no functional group

(d) define isomerism and identify isomers

Point Content Examples

Isomers Organic compounds with the same molecular formulae but different structural formulae

Methylpropane and Butane are isomers.

But-1-ene and But-2-ene are isomers.

(e) describe the properties of alkanes (exemplified by methane) as being generally unreactive except in terms of

burning and substitution by chlorine

Point Content

Alkanes are unreactive Carbon-carbon and Carbon-hydrogen are strong and difficult to break.

Except in burning Complete: Methane + Oxygen (with heat) Carbon dioxide + Water vapour Incomplete: Methane + Oxygen (with heat) Carbon monoxide + Water vap.

Except in substitution Methane + Chlorine (UV light) Chloromethane + Hydrogen chloride (Cl atom replaces a H atom)

11.3: Alkenes

(a) describe the alkenes as an homologous series of unsaturated hydrocarbons with the general formula CnH2n

Point Content

Saturated Hydrocarbons containing only double (C=C) or triple (CΞC) covalent bonds

(c) describe the manufacture of alkenes and hydrogen by cracking hydrocarbons and recognise that cracking is

essential to match the demand for fractions containing smaller molecules from the refinery process

Point Cracking of Products Importance

Main reaction Alkane Alkene + Alkane of shorter chain Short-chained alkanes are used as

petrol Alkane Alkene + Hydrogen

Side reaction Alkane Alkene + Alkene + Hydrogen Hydrogen used to make ammonia

Catalysts Al2O3 (amphoteric), SiO2 (acidic giant covalent) Speed up cracking process

(d) describe the difference between saturated and unsaturated hydrocarbons from their molecular structures and by

using aqueous bromine

Point Saturated hydrocarbon Unsaturated hydrocarbon

Double bonds Contain only single bonds between carbon atoms Contain double bonds between carbon atoms

Reactivity Generally unreactive (The carbon-hydrogen and carbon-carbon bonds are unreactive)

Very reactive (The carbon-oxygen and oxygen-hydrogen bonds are more reactive)

Reactions Substitution reactions Addition polymeristion

Combustion Produce less smoky flames than alkanes with same numbers of carbon atoms as they have a higher percentage of carbon atoms per mole

Produce smokier flames than alkanes with same numbers of carbon atoms

Aqueuous bromine

Do not react with bromine solution under normal conditions

Decolourises aqueous orange-brown bromine solution

(e) describe the properties of alkenes (exemplified by ethene) in terms of combustion, polymerisation and the

addition reactions with bromine, steam and hydrogen

Point Reactants Conditions Products

Combustion Alkene + Oxygen Heat, Air in plentiful supply Carbon dioxide + Water vap

With hydrogen Alkene + Hydrogen 200oC, Nickel catalyst Alkane

With steam Alkene + Steam 300oC, 60 atm, Phosphoric IV acid Alcohol

With bromine Alkene + Bromine Normal conditions Bromoalkane

Polymerisation Occurs when monomer units join together without losing any molecules or atoms

(f) state the meaning of polyunsaturated when applied to food products

Point Meaning

Polyunsaturated Food products by which their hydrocarbon chains contain more than one carbon-carbon double bond

(g) describe the manufacture of margarine by the addition of hydrogen to unsaturated vegetable oils to form a solid product

Point Manufacture additives

Production of margarine Hydrogen + Vegetable oil + 200oC + Nickel catalyst

Purpose Hardening Main constituent Heat Catalyst

11.4: Alcohols

(a) describe the alcohols as an homologous series containing the -OH group

(c) describe the properties of alcohols in terms of combustion and oxidation to carboxylic acids

Point Reactants Conditions Products

Combustion Alcohol + oxygen Heat, plentiful oxygen Carbon dioxide + Steam

Oxidation Alcohol + oxygen from oxidising agent Heat Carboxylic acid + Water

Bacterial Ethanol + oxygen in air Bacteria presence Ethanoic acid + Water

Oxidising agents

Acidified potassium dichromate (VI) changes from orange to green (OG) Acidified potassium manganate (VII) changes from purple to colourless (PC)

Reduces 2 O atoms

(d) describe the formation of ethanol by the catalysed addition of steam to ethene and by fermentation of glucose

Point Reactants Conditions Products

Catalysed addition of steam Ethene + Steam 300oC, 60 atm, Phosphoric IV acid Ethanol

Fermentation of glucose Glucose solution 37-40oC, Absence of oxygen Ethanol + CO2

Max 20% ethanol

(e) state some uses of ethanol, e.g. as a solvent; as a fuel; as a constituent of alcoholic beverages

Uses Content

Solvent Good solvent to dissolve substances insoluble in water

Evaporates quickly

Fuel Reactants Product Function

85% Ethanol + 5% Methanol + 10% Water Methylated spirit Cooking, lamps

Ethanol + Petrol Fuel Run motor vehicles

Alcholic beverages by fer-mentation

Barley starch solution 3-8% Ethanol + CO2 Beer

Barley starch solution + Fractional distill. 30-60% Ethanol + CO2 Whisky

Grapes starch solution 8-18% Ethanol + CO2 Wine

Grapes starch solution + Fractional distill. 30-60% Ethanol + CO2 Brandy

11.5: Carboxylic acids

(c) describe the carboxylic acids as weak acids, reacting with carbonates, bases and some metals

Reaction with Reactants Products

Carbonates Ethanoic acid + Metal carbonate Metal ethanoate + Carbon dioxide + Water

Bases Ethanoic acid + Base Metal ethanoate + Water

Metals Ethanoic acid + Reactive metal (PM) Metal ethanoate + Hydrogen

1. Carboxylic acids ionise only partially in water to form hydrogen ions, hence they are weak acids

2. The hydrogen ions that are formed in water give carboxylic acids their acidic properties.

To form the metal ethanoate, 1. Take away the ending H atom from acid 2. Then C...H...COO- + Metal ion Ethanoate

(d) describe the formation of ethanoic acid by the oxidation of ethanol by atmospheric oxygen or acidified potassium dichromate(VI)

Point Reactants Conditions Products

Oxidation Alcohol + Oxygen from oxidising agent Heat Carboxylic acid + Water

Bacterial Ethanol + Oxygen in air Bacteria presence Ethanoic acid + Water

Oxidising agents

Acidified potassium dichromate (VI) changes from orange to green (OG) Acidified potassium manganate (VII) changes from purple to colourless (PC)

Reduces 2 O atoms

(e) describe the reaction of a carboxylic acid with an alcohol to form an ester, e.g. ethyl ethanoate

Esterification Description of formation

The reaction of a carboxylic acid with an alcohol to form an organic compound known as an ester (through warming and presence of few drops of concentrated sulfuric acid as a catalyst)

The -OH group of the carboxylic acid of is replaced the CnH2n+1O- group of an alcohol.

Point Reactants Conditions Products

Esterification Alcohol + Carboxylic acid Heat, Conc sulfuric acid Ester + Water

(f) state some commercial uses of esters, e.g. perfumes; flavourings; solvents

Characteristics Suitable for

Colourless, netural, water insoluble, sweet and fruity smell Perfumes and artificial food flavourings

Cosmetics and glues constituents soluble in organic solvents Solvents for cosmetics and glues

11.6: Macromolecules

(a) describe macromolecules as large molecules built up from small units, different macromolecules having different units and/or different linkages

Point Definition / Description Key words

Monomer A small molecule that can be joined together to form a polymer (larger molecule)

1. Small molecule 2. Can join to form polymer

Polymer A macromolecule (long-chain molecule) made up of many monomers (small molecules) joined together

1. Macromolecule 2. Monomers joined together

Macromolecule A long-chain molecule that contains hundreds or thousands of atoms joined together by covalent bonds

1. Long-chain 2. 103 or 104 s of atoms 3. Covalently bonded

Polymerisation Process of joining together a large number of monomers (small molecules) to form a macromolecule (large molecule)

(b) describe the formation of poly(ethene) as an example of addition polymerisation of ethene as the monomer

Point Definition / Description

Addition polymerisation

Process of joining together monomer units without using any molecules or atoms

General reaction Thousands of alkene molecules Polymer (at 200oC, 1000 atm)

Example Thousands of ethene molecule Poly(ethene) (at 200oC, 1000 atm, Ziegler’s catalyst)

Step to form poly(ethene) Definition / Description

1. Bond breaking One bond in the double bond of each ethene molecule breaks

2. Bonding with other monomers Each ethene molecule forms single bonds with two other monomers

3. Poly(ethene) formed Poly(ethene) is formed under high pressure and temperature

(c) state some uses of poly(ethene) as a typical plastic, e.g. plastic bags; clingfilm

Characteristics Suitable for

Flexible but difficult to break Plastic bags

Clingfilm

(e) describe nylon, a polyamide, and Terylene, a polyester, as condensation polymers, the partial structure representations of nylon and that of Terylene

Point Nylon Terylene

Type Polyamide Polyester (poly-ester, ‘many ester linkages’)

Reactants Dicarboxylic acid (2 -COOH)

Diamine (2 -NH2)

Dicarboxylic acid (2 -COOH)

Diol (2 -OH)

Specific reactants

- Benzene-1, 4-Dicarboxylic acid

Ethane-1, 2-Diol

Functional group Amide group

Ester functional

group ―COO―

―CONH―

Partial structure

(g) describe the pollution problems caused by the disposal of non-biodegradable plastics

Problems Fires spread Produces poisonous gases when spread Non-biodegradable Air pollution

Description Modern buildings are insulated and furnished with plastic

Contains carbon compounds

Highly flammable

Cannot be decomposed by bacteria in soil

Land pollution

PVC produces hydrogen chloride gas

Solutions Reuse or recycle plastics

Summary of reactions in organic chem

Reactants Products Conditions Catalysts Alkane + Oxygen in air Carbon dioxide + Water vapour Heat, abundant oxygen supply -

Alkene + Oxygen in air Carbon dioxide + Water vapour Heat, abundant oxygen supply -

Alcohol + Oxygen in air Carbon dioxide + Steam Heat, abundant oxygen supply -

Alkane + Oxygen when incomplete Carbon monoxide + Water vapour Heat, limited supply of oxygen - Alcohol + Oxygen from oxidising agent Carboxylic acid + Water Heat -

Ethanol + Oxygen in air Ethanoic acid + Water Presence of bacteria - Alkane main cracking reaction Alkene + Alkane of shorter chain 600oC Al2O3/SiO2

Alkane possible cracking reaction Alkene + Hydrogen 600oC Al2O3/SiO2

Alkane side cracking reaction Alkene + Alkene + Hydrogen 600oC Al2O3/SiO2

Alkane + Chlorine Chloroalkane + Hydrogen chloride UV light - Alkene + Hydrogen Alkane 200oC Nickel

Vegetable oil + Hydrogen Margarine 200oC Nickel Alkene + Bromine Bromoalkane - -

Alkene + Steam Alcohol 300oC, 60 atm Phosphoric (IV) acid Glucose solution dilute 15% Ethanol + Carbon dioxide 37-40oC, Absence of oxygen Yeast (enzyme)

Alcohol + Carboxylic acid Ester + Water Heat Concentrated Sulfuric acid