Organic Families (Cambridge (CIE) IGCSE Chemistry)

Propane reacts with chlorine to form a mixture of chloropropanes. This is a photochemical reaction.

i) What is meant by the phrase photochemical reaction?

[1]

ii) The products of this reaction include two isomers, one of which has the following structural formula.

   Draw the structural formula of the other isomer.

[1]

iii) Explain why these two different compounds are isomers.

[2]

Bond breaking is an endothermic change and bond forming is an exothermic change.  Bond energy is the amount of energy in kJ / mol needed to break one mole of the specified bond.

Use the following bond energies to determine whether this reaction is exothermic or endothermic. You must show your reasoning.

i) Chloropropane can be hydrolysed to propanol, CH₃CH₂CH₂OH, by sodium hydroxide. Write the equation for this reaction.

[2]

ii) Propanol can be dehydrated. It loses a water molecule to form a hydrocarbon.

Give the name and structural formula of this hydrocarbon.

[2]

iii) Propanol is oxidised to a carboxylic acid by acidified potassium manganate(VII).

Deduce the name of this acid.

[1]

Propanol reacts with methanoic acid to form the ester propyl methanoate.

CH₃CH₂CH₂OH + HCOOH → HCOOCH₂CH₂CH₃ + H₂O

4.0 g of methanoic acid was reacted with 6.0 g of propanol.

i) Calculate the M_r of methanoic acid.

[1]

ii) Calculate the M_r of propanol.

[1]

iii) Determine which one is the limiting reagent. Show your reasoning.

[2]

iv) Calculate the maximum yield in grams of propyl methanoate, M_r = 88.

[1]

The alkenes are a series of unsaturated hydrocarbons. They have the general molecular formula C_nH_2n.

Deduce the molecular formula of an alkene which has a relative molecular mass of 126.

Show your working.

The structural formula of propene is drawn below.  

i) Draw a diagram showing the arrangement of the valency electrons in one molecule of this covalent compound.

 Use x to represent an electron from an atom of carbon.

Use o to represent an electron from an atom of hydrogen.

 [3]

 ii) Draw the structure of the polymer formed from propene

 [2]

 iii) Bond energy is the amount of energy, in kJ, which must be supplied to break one mole of the bond. 

 Use the data in the table to show that the following reaction is exothermic.

[3]

This question is concerned with some of the addition reactions of but-1-ene.

 i) Name the product formed when but-1-ene reacts with water.

 [1]

 ii) Complete the equation.

 CH₃–CH₂–CH=CH₂ + Br₂ → .....................................................................

 [2]

 iii) Deduce the formula of the compound which reacts with but-1-ene to form 1-iodobutane.

 [1] 

The alcohols form a homologous series.

i) Give three characteristics which all members of a homologous series share.

[3]

ii) Give the name of the third member of this series.

[1]

iii) Deduce the molecular formula of the alcohol whose M_r = 158. Show your working.

[2]

Explain why the following two alcohols are isomers.

This question is based on typical reactions of butan-1-ol.

i) When butan-1-ol, CH₃–CH₂–CH₂–CH₂–OH, is passed over the catalyst silicon(IV) oxide, water is lost. Deduce the name and the structural formula of the organic product in this reaction.

[2]

ii) Suggest the name of the ester formed from butanol and ethanoic acid.

[1]

iii) Butan-1-ol is oxidised by acidified potassium manganate(VII).

Deduce the name and the structural formula of the organic product in this reaction.

[2]

Alcohols can be made by fermentation or from petroleum.

Ethanol can be made by the fermentation of glucose.

C₆H₁₂O₆ (aq) 2C₂H₅OH (aq) + 2CO₂ (g)       exothermic reaction

Yeast are living single-cell fungi which ferment glucose by anaerobic respiration. This reaction is catalysed by enzymes from the yeast.

i) What are enzymes?

[1]

ii) Suggest a method of measuring the rate of this reaction.

[1]

The following observations were noted.

• When a small amount of yeast was added to the aqueous glucose the reaction started and the solution went slightly cloudy.

• The reaction rate increased and the solution became cloudier and warmer.

• After a while, the reaction rate decreased and eventually stopped, leaving a 14% solution of ethanol in water.

i) Why did the reaction rate increase?

[1]

ii) Suggest an explanation for the increase in cloudiness of the solution.

[1]

iii) Give two reasons why the fermentation stopped.

[2]

One use of ethanol is in alcoholic drinks.

Give two other uses of ethanol.

Alcohols can be made from petroleum by the following sequence of reactions.

alkanes from petroleum → alkene → alcohol

Describe the manufacture of ethanol from hexane, C₆H₁₄. Include in your description an equation and type of reaction for each step.

The ester linkage showing all the bonds is drawn as

or more simply it can be written as –COO–.

i) Give the structural formula of the ester ethyl ethanoate.

[1]

ii) Deduce the name of the ester formed from methanoic acid and butanol.

[1]

Draw the structural formula of the polyester formed from the following monomers.

HOOCC₆H₄COOH and HOCH₂CH₂OH

You are advised to use the simpler form of the ester linkage.

Esters can be used as solvents in chromatography. The following shows a chromatogram of plant acids.

An ester was used as the solvent and the chromatogram was sprayed with bromothymol blue.

i) Suggest why it was necessary to spray the chromatogram.

[2]

ii) Explain what is meant by the R_f value of a sample.

[1]

iii) Calculate the R_f values of the two samples and use the data in the table to identify the plant acids.

[2]

The alcohols form a homologous series. The first member of this series is methanol, CH₃OH.

i) Give the general formula of the alcohols.

[1]

ii) The mass of one mole of an alcohol is 116 g. What is its formula? Show your reasoning.

[2]

ii) Draw a diagram showing the arrangement of the outer (valency) electrons in one molecule of methanol.

Use x to represent an electron from a carbon atom.
Use o to represent an electron from a hydrogen atom.
Use ● to represent an electron from an oxygen atom.

[3]

Methanol is manufactured using the following method.

CH₄ (g) + H₂O (g) → CO (g) + 3H₂ (g)   reaction 1 CO (g) + 2H₂ (g) CH₃OH (g)    reaction 2

The conditions for reaction 2 are:

The forward reaction is exothermic.

i) Why is high pressure used in reaction 2?

[2]

ii) Explain why using a catalyst at 250 °C is preferred to using a higher temperature of 350°C and no catalyst.

[3]

Methanol is oxidised by atmospheric oxygen. This reaction is catalysed by platinum.

i) The products of this reaction include a carboxylic acid. Give its name and structural formula.

[2]

ii) Deduce the name of the ester formed by the reaction of methanol with the carboxylic acid named in (i).

[1]

Propenoic acid is an unsaturated carboxylic acid. The structural formula of propenoic acid is given below.

i) Describe how you could show that propenoic acid is an unsaturated compound. 

Test:

Result:

[2]

ii) Without using an indicator, describe how you could show that a compound is an acid.

Test:

Result:

[2]

Propenoic acid reacts with ethanol to form an ester. Deduce the name of this ester. Draw its structural formula.

Name of ester:

Structural formula showing all bonds:

An organic compound has a molecular formula C₆H₈O₄. It is an unsaturated carboxylic acid. One mole of the compound reacts with two moles of sodium hydroxide.

i) Explain the phrase molecular formula.

[2]

ii) One mole of this carboxylic acid reacts with two moles of sodium hydroxide. How many moles of –COOH groups are there in one mole of this compound?

[1]

iii) What is the formula of another functional group in this compound?

[1]

iv) Deduce a structural formula of this compound.

[1]

Alkanes and alkenes are both series of hydrocarbons.

i) Explain the term hydrocarbon.

[1]

ii) What is the difference between these two series of hydrocarbons?

[2]

Alkenes and simpler alkanes are made from long-chain alkanes by cracking.

Complete the following equation for the cracking of the alkane C₂₀H₄₂.

C₂₀H₄₂  → 2C₄H₈ + 2C₂H₄ + ...............

Alkenes such as butene and ethene are more reactive than alkanes.

Alkenes are used in the petrochemical industry to make a range of products, which includes polymers and alcohols.

i) Dibromoethane is used as a pesticide. Complete the equation for its preparation from ethene.

[1]

ii) The structural formula of a poly(alkene) is given below.

Deduce the structural formula of its monomer.

[2]

iii) How is butanol made from butene, CH₃ –CH₂ –CH=CH₂? Include an equation in your answer.

[2]

iv) Cracking changes alkanes into alkenes. How could an alkene be converted into an alkane?

Include an equation in your answer.

[2]

20 cm³ of a hydrocarbon was burnt in 175 cm³ of oxygen. After cooling, the volume of the remaining gases was

125 cm³. The addition of aqueous sodium hydroxide removed carbon dioxide leaving 25 cm³ of unreacted oxygen.

Volume of oxygen used = .......... cm³

[1]

Volume of carbon dioxide formed = .......... cm³

[1]

Deduce the formula of the hydrocarbon and the balanced equation for the reaction.

[2]

The structural formula of a butanol is given below.

CH₃—CH₂—CH₂—CH₂—OH

Butanol can be made from petroleum and also by fermentation.

i) Describe the chemistry of making butanol from petroleum by the following route.

petroleum → butene → butanol

[3]

ii) Explain, in general terms, what is meant by fermentation.

[3]

Butanol can be oxidised to a carboxylic acid by heating with acidified potassium manganate(VII). Give the name and structural formula of the carboxylic acid.

Butanol reacts with ethanoic acid to form a liquid, X, which has the sweet smell of bananas. Its empirical formula is C₃H₆O and its M_r is 116.

i) What type of compound is liquid X?

[1]

ii) Give the molecular formula of liquid X.

[1]

iii) Draw the structural formula of X. Show all the individual bonds.

[2]

But-1-ene is a typical alkene. It has the structural formula shown below.

CH₃–CH₂–CH=CH₂

The structural formula of cyclobutane is given below.

These two hydrocarbons are isomers.

 i) Define the term isomer.

 [2]

 ii) Draw the structural formula of another isomer of but-1-ene.

 [1]

 iii) Describe a test which would distinguish between but-1-ene and cyclobutane.

 reagent ..................................................

 result with but-1-ene ..................................................

 result with cyclobutane ..................................................

 [3]

Describe how alkenes, such as but-1-ene, can be made from alkanes.

Name the product formed when but-1-ene reacts with:

 bromine, ..........................................................................................................

[1]

 hydrogen, ..........................................................................................................

[1]

 steam. ..........................................................................................................

[1]

The alcohols form an homologous series.

Give three characteristics of a homologous series.

The following two alcohols are members of the series and they are isomers.

CH₃—CH₂—CH₂—CH₂—OH and (CH₃)₂CH—CH₂OH

i) Explain why they are isomers.

[2]

ii) Give the structural formula of another alcohol which is also an isomer of these alcohols.

[1]

Copper(II) oxide can oxidise butan-1-ol to liquid X whose pH is 4.

i) Name another reagent which can oxidise butan-1-ol.

[1]

ii) What type of compound is liquid X and what is its formula?

[2]

The alcohol ethanol can be made by fermentation. Yeast is added to aqueous glucose.

C₆H₁₂O₆ (aq) → 2C₂H₅OH (aq) + 2CO₂ (g)

Carbon dioxide is given off and the mixture becomes warm as the reaction is exothermic. The graph shows how the rate of reaction varies over several days.

i) Suggest a method of measuring the rate of this reaction.

[2]

ii) Why does the rate increase initially?

[1]

iii) Suggest two reasons why the rate eventually decreases.

[2]

iv) Why is fermentation carried out in the absence of air?

[1]

The alcohols form a homologous series. Two characteristics of a homologous series are that the physical properties of the members vary in a predictable way and they have similar chemical properties.

Complete the table.

Give two other characteristics of a homologous series.

Draw a diagram showing the arrangement of the valency electrons in one molecule of the covalent compound methanol.

Use x to represent an electron from a carbon atom.
Use ● to represent an electron from an oxygen atom.
Use o to represent an electron from a hydrogen atom.

Alcohols can be oxidised to carboxylic acids by heating with acidic potassium manganate(VII).

i) Draw the structural formula of the carboxylic acid formed by the oxidation of propan-1-ol. Show all the bonds.

[1]

ii) Describe how ethanol could be oxidised to ethanoic acid by fermentation.

[2]

Propan-1-ol and ethanoic acid react together to form an ester. Give its name and structural formula.

The alkenes are a homologous series of unsaturated hydrocarbons.

The table below gives the names, formulae and boiling points of the first members of the series.

i) Complete the table by giving the formula of hexene and by predicting its boiling point.

[2]

ii) Deduce the formula of the alkene which has a relative molecular mass of 168. Show your working.

[2]

Describe a test that will distinguish between the two isomers, but-2-ene and cyclobutane.

test ..........................................................................................................

result with but-2-ene  ..........................................................................................................

result with cyclobutane  ..........................................................................................................

Alkenes undergo addition reactions.

i) What class of organic compound is formed when an alkene reacts with water?

[1]

ii) Draw the structure of the polymer formed from but-2-ene.

[2]

Two homologous series of hydrocarbons are the alkanes and the alkenes.

One general characteristic of a homologous series is that the physical properties vary in a predictable way.

i) State three other general characteristics of a homologous series.

[3]

ii) How can the molecular formula of a hydrocarbon show whether it is an alkane or an alkene?

[2]

iii) How do alkanes and alkenes differ in their molecular structures?

[2]

Cracking is the thermal decomposition of alkanes into smaller hydrocarbons and possibly hydrogen.

i) State two conditions required for the cracking of an alkane.

[2]

ii) One type of cracking produces an alkane and an alkene. Complete an equation for the cracking of heptane into an alkane and an alkene.

C₇H₁₆ → ................ + ................ 

[1]

iii) Complete an equation for the cracking of heptane into hydrogen and two other products.

C₇H₁₆  →................ + ................ + H₂

[1]

iv) Suggest one reason why cracking is important.

 [1]

Hydrocarbons burn in excess oxygen to form carbon dioxide and water. 20 cm³ of a gaseous hydrocarbon burned in an excess of oxygen, 200 cm³. After cooling, the volume of the residual gas at r.t.p. was 150 cm³, 50 cm³ of which was oxygen.

i) Determine the volume of the oxygen used.

[1]

ii) Determine the volume of the carbon dioxide formed.

[1]

The fractional distillation of crude oil usually produces large quantities of the heavier fractions. The market demand is for the lighter fractions and for the more reactive alkenes. The heavier fractions are cracked to form smaller alkanes and alkenes as in the following example.

C₈H₁₈ → C₄H₁₀ +      C₄H₈

octane butane  butene

i) Write a different equation for the cracking of octane.

 C₈H₁₈ → .............................. + ..............................

 [1]

 ii) The cracking of octane can produce isomers with the molecular formula C₄H₈.

 Draw the structural formulae of two of these isomers.

 [2]

i) Give the essential condition for the reaction between chlorine and butane.

[1]

ii) What type of reaction is this?

[1]

iii) This reaction produces a mixture of products. Give the names of two products that contain four carbon atoms per molecule.

................................... and ......................................

[2]

Alkenes are more reactive than alkanes and are used to make a range of organic chemicals. Propene, CH₃–CH=CH₂, is made by cracking. Give the structural formula of the addition product when propene reacts with the following.

 i) water

 [1]

 ii) bromine

 [1]

Propene reacts with hydrogen iodide to form 2-iodopropane.

CH₃−CH=CH₂ + HI → CH₃−CHI−CH₃

1.4 g of propene produced 4.05 g of 2-iodopropane.

Calculate the percentage yield.

moles of CH₃–CH=CH₂ reacted = ..................................................

maximum moles of CH₃–CHI–CH₃ that could be formed = ..................................................

mass of one mole of CH₃–CHI–CH₃ = 170 g

maximum mass of 2- iodopropane that could be formed = ..................................................

percentage yield .................................................. %

The alcohols form a homologous series. The first four members are methanol, ethanol, propan-1-ol and butan-1-ol.

One characteristic of a homologous series is that the physical properties vary in a predictable way. The table below gives the heats of combustion of the first three alcohols.

i) The minus sign indicates that there is less chemical energy in the products than in the reactants. What form of energy is given out by the reaction?

[1]

ii) Is the reaction exothermic or endothermic?

[1]

iii) Complete the equation for the complete combustion of ethanol.

[2]

iv) Determine the heat of combustion of butan-1-ol by plotting the heats of combustion of the first three alcohols against the number of carbon atoms per molecule.

[3]

v) Describe two other characteristics of homologous series.

[2]

Give the name and structural formula of an isomer of propan-1-ol.

Methanol is made from carbon monoxide.

CO (g) + 2H₂(g) CH₃OH (g) the forward reaction is exothermic

i) Describe how hydrogen is obtained from alkanes.

[2]

ii) Suggest a method of making carbon monoxide from methane.

[2]

iii) Which condition, high or low pressure, would give the maximum yield of methanol? Give a reason for your choice.

[2]

For each of the following predict the name of the organic product.

i) reaction between methanol and ethanoic acid

[1]

ii) oxidation of propan-1-ol by potassium dichromate(VI)

[1]

iii) removal of H₂O from ethanol (dehydration)

[1]

A hydrocarbon has the following structural formula.

i) State the molecular formula and the empirical formula of this hydrocarbon.

  molecular formula ..........................................................................................................

empirical formula ..........................................................................................................

[2]

ii) Draw the structural formula of an isomer of the above hydrocarbon.

 [1]

iii) Explain why these two hydrocarbons are isomers.

[2]

iv) Are these two hydrocarbons members of the same homologous series? Give a reason for your choice.

 [1]

Alkenes can be made from alkanes by cracking.

i) Explain the term cracking.

[2]

ii) One mole of an alkane, when cracked, produced one mole of hexane, C₆H₁₄, and two moles of ethene.

What is the molecular formula of the original alkane?

[1]

Alkenes are used in polymerisation reactions and addition reactions.

i) Draw the structural formula of the product formed by the addition polymerisation of but-2-ene. Its formula is given below.

[3]

ii) Give the name and structural formula of the addition product formed from ethene and bromine.

name ..........................................................................................................

structural formula

[2]

The fractional distillation of crude oil usually produces large quantities of the heavier fractions.

The market demand is for the lighter fractions and for the more reactive alkenes. The heavier fractions are cracked to form smaller alkanes and alkenes as in the following example.

 i) Write a different equation for the cracking of octane.

C₈H₁₈  → ...................... + .....................

[1]

ii) The cracking of octane can produce isomers with the molecular formula C₄H₈. Draw the structural formulae of two of these isomers.

[2]

i) Give the essential condition for the reaction between chlorine and butane.

[1]

ii) What type of reaction is this?

[1]

iii) This reaction produces a mixture of products. Give the names of two products that contain four carbon atoms per molecule.

[2]

Alkenes are more reactive than alkanes and are used to make a range of organic chemicals. Propene, CH₃–CH=CH₂, is made by cracking. Give the structural formula of the addition product when propene reacts with the following.

 i) water

[1]

 ii) bromine

[1]

Propene reacts with hydrogen iodide to form 2-iodopropane.

CH₃−CH=CH₂ + HI →  CH₃−CHI−CH₃

1.4 g of propene produced 4.0 g of 2-iodopropane. Calculate the percentage yield.

moles of CH₃–CH=CH₂ reacted = .........................................

maximum moles of CH₃–CHI–CH₃ that could be formed = .........................................

mass of one mole of CH₃–CHI–CH₃ = 170 g

maximum mass of 2- iodopropane that could be formed = .........................................

percentage yield ......................................... %

The alkenes are unsaturated hydrocarbons. They form a homologous series, the members of which have the same chemical properties.

They undergo addition reactions and are easily oxidised.

The following hydrocarbons are isomers.

i) Explain why these two hydrocarbons are isomers.

[2]

ii) Give the structural formula of another hydrocarbon which is isomeric with the above.

[1]

Give the structural formula and name of each of the products of the following addition reactions.

i) ethene and bromine structural formula of product

name of product ................................................................................................... 

[2]

ii) propene and hydrogen structural formula of product

name of product ................................................................................................... 

[2]

iii) but-1-ene and water structural formula of product

name of product ................................................................................................... 

[2]

Alkenes can be oxidised to carboxylic acids.

i) For example, propene, CH₃ –CH=CH₂, would produce ethanoic acid, CH₃ –COOH, and methanoic acid, H–COOH.

Deduce the formulae of the alkenes which would form the following carboxylic acids when oxidised.

ethanoic acid and propanoic acid

only ethanoic acid

[2]

 ii) Describe the colour change you would observe when an alkene is oxidised with acidified potassium manganate(VII).

[2]

Alkenes polymerise to form addition polymers.

Draw the structural formula of poly(cyanoethene), include at least two monomer units.

The structural formula of the monomer, cyanoethene, is given below.

The alkenes are unsaturated hydrocarbons. They form a homologous series, the members of which have similar chemical properties

•  easily oxidised    

• addition reactions    

• polymerisation    

• combustion.

All the alkenes have the same empirical formula.

i) State their empirical formula.

[1]

ii) Why is the empirical formula the same for all alkenes?

[1]

Alkenes can be oxidised to carboxylic acids by boiling with aqueous potassium manganate(VII).

i) Pent-2-ene, CH₃–CH₂–CH=CH–CH₃, oxidises to CH₃–CH₂–COOH and CH₃COOH.

Name these two acids.

CH₃–CH₂–COOH .......................................................................................................

CH₃COOH ..........................................................................................................

[2]

ii) Most alkenes oxidise to two carboxylic acids. Deduce the formula of an alkene which forms only one carboxylic acid.

[1]

Complete the following equations for the addition reactions of propene.

CH₃–CH=CH₂ + Br₂ → .................................... 

CH3–CH=CH₂ + H₂O → ....................................

Draw the structural formula of poly(propene).

0.01 moles of an alkene needed 2.4 g of oxygen for complete combustion. 2.2 g of carbon dioxide were formed.

Determine the following mole ratio.

moles of alkene : moles of O₂ : moles of CO₂

From this ratio determine the formula of the alkene.

[3]

Write an equation for the complete combustion of this alkene.

[1]

Many organic compounds which contain a halogen have chloro, bromo or iodo in their name.

The following diagram shows the structure of 1-chloropropane.

i) Draw the structure of an isomer of this compound.

[1]

ii) Describe how 1-chloropropane could be made from propane.

[2]

iii) Suggest an explanation why the method you have described in (ii) does not produce a pure sample of 1-chloropropane.

[2]

Organic halides react with water to form an alcohol and a halide ion.

CH₃–CH₂–I + H₂O → CH₃–CH₂–OH + I^–

i) Describe how you could show that the reaction mixture contained an iodide ion.

[2]

ii) Name the alcohol formed when 1-chloropropane reacts with water.

[1]

The speed (rate) of reaction between an organic halide and water can be measured by the following method.

A mixture of 10 cm³ of aqueous silver nitrate and 10 cm³ of ethanol is warmed to 60 °C.

Drops of the organic halide are added and the time taken for a precipitate to form is measured.

Silver ions react with the halide ions to form a precipitate of the silver halide.

Ag⁺ (aq) + X^- (aq) → AgX (s)

Typical results for four experiments, A, B, C and D, are given in the table.

i) Explain why it takes longer to produce a precipitate in experiment A than in B.

[2]

ii) How does the order of reactivity of the organic halides compare with the order of reactivity of the halogens?

[2]

iii) Explain why the time taken to produce a precipitate would increase if the experiments were repeated at 50 °C.

[3]

Petroleum is a source of many important chemicals.

Name two industrial processes which must take place to produce alkenes from petroleum.

Ethene, CH₂=CH₂, and propene, CH₂=CHCH₃, can both be converted into polymers.

 i) What type of polymerisation takes place when ethene forms a polymer?

[1]

ii) What is the empirical formula of the polymer formed from ethene?

[1]

iii) Propene has the structural formula CH₂=CHCH₃.

Draw two repeat units of the polymer made from propene.

[2]

Ethene will react with steam to form ethanol.

Propene will react with steam to form two isomers, both of which are alcohols.

Suggest the structures of these alcohols.

Esters are organic chemicals noted for their characteristic smells. Ethanoic acid and methanol will react to form an ester.

i) Name the catalyst needed to form an ester from ethanoic acid and methanol.

[1]

ii) Name the ester formed when ethanoic acid reacts with methanol.

[1]

iii) Draw the structure of the ester formed when ethanoic acid reacts with methanol. Show all bonds.

[2]

iv) Give the name of a polyester.

[1]

Propanoic acid is a carboxylic acid. Its formula is CH₃–CH₂–COOH.

 i) Propanoic acid is the third member of the homologous series of carboxylic acids.

 Give the name and structural formula of the fourth member of this series.

  Name ..............................................................

  Formula ..............................................................

[2]

ii) Members of a homologous series have very similar chemical properties.

 State three other characteristics of a homologous series.

[3]

Carboxylic acids can be made by the oxidation of alcohols.

 i) Draw the structural formula of the alcohol which can be oxidised to propanoic acid. Show all atoms and bonds.

[1]

ii) Name a reagent, other than oxygen, which can oxidise alcohols to carboxylic acids.

[2]

Complete the following equations for some of the reactions of propanoic acid.

The salts of this acid are called propanoates.

 i) Zinc + propanoic acid → ........................... ........................... + hydrogen

[1]

ii) Calcium oxide + propanoic acid →........................... + ...........................

[1]

iii) LiOH + CH₃CH₂COOH → ............................... + ...........................

[1]

A piece of magnesium was added to 100 cm³ of an aqueous acid. The time taken for the metal to react completely was measured.

This experiment was repeated using different aqueous acids. The same volume of acid was used in each experiment and the pieces of magnesium used were identical.

In one experiment the reaction was carried out at a different temperatur

Explain the following in terms of collision rate between reacting particles.

i) Why is the rate in experiment C slower than the rate in experiment A? 

[2]

ii) Why is the rate in experiment B faster than the rate in experiment A?

[2]

iii) Why is the rate in experiment D faster than the rate in experiment A?

[3]

Plants can make complex molecules from simple starting materials, such as water, carbon dioxide and nitrates. Substances produced by plants include sugars, more complex carbohydrates, esters, proteins, vegetable oils and fats.

i) Describe how you could decide from its molecular formula whether a compound is a carbohydrate.

 [2]

 ii) Plants can change the sugar, glucose, into starch which is a more complex carbohydrate. What type of reaction is this?

 [2]

The fermentation of glucose can be carried out in the apparatus shown below. After a few days the reaction stops. A 12% aqueous solution of ethanol has been produced.

 i) The enzyme, zymase, catalyses the anaerobic respiration of the yeast.

 Explain the term respiration.

 [2]

 ii) Complete the equation.

 [2]

 iii) Why must air be kept out of the flask?

 [1]

The ester methyl butanoate is found in apples. It can be made from butanoic acid and methanol. Their structural formulae are given below.

butanoic acid	methanol

 Use the information given above to deduce the structural formula of methyl butanoate showing all the bonds.

Proteins are natural macromolecules. Draw the structural formula of a typical protein. Include three monomer units. You may represent amino acids by formulae of the type drawn below.

Methanol can be made from a mixture of carbon monoxide and hydrogen.

CO (g) + 2H₂ (g) CH₃OH (g)

The forward reaction is exothermic.

i) Explain why the concentration of methanol at equilibrium does not change.

[2]

ii) Suggest conditions, in terms of temperature and pressure, which would give a high yield of methanol.

[2]

iii) How would the conditions used in practice compare with those given in (ii)? Give an explanation of any differences.

[2]

Petroleum-based diesel is a mixture of hydrocarbons, such as octane and octene.

i) ‘Oct’ means eight carbon atoms per molecule. Draw a structural formula of an octene molecule.

[1]

ii) Describe a test which would distinguish between octane and octene. Test: Result with octane: Result with octene:

[3]

Structural formulae are an essential part of Organic Chemistry.

Draw the structural formula of each of the following. Show all the bonds in the structure.

i) ethanoic acid

[1]

ii) ethanol

[1]

Ethanoic acid and ethanol react to form an ester.

i) What is the name of this ester?

[1]

ii) The same linkage is found in polyesters. Draw the structure of the polyester which can be formed from the monomers shown below.

HOOC—C₆H₄—COOH and HO—CH₂—CH₂—OH

[3]

iii) Describe the pollution problems caused by non-biodegradable polymers.

[2]

Two macromolecules have the same amide linkage. Nylon, a synthetic polymer, has the following structure.

Protein, a natural macromolecule, has the following structure.

How are they different?

Carboxylic acids contain the group

Ethanoic acid is a typical carboxylic acid. It forms ethanoates.

i) Complete the following equations.

Mg + ......CH₃COOH → ............................... + ...............................

[2]

sodium hydroxide + ethanoic acid → ........................  ........................ + ........................

[1]

ii) Ethanoic acid reacts with ethanol to form an ester. Give the name of the ester and draw its structural formula. Show all of the bonds.

[2]

Maleic acid is an unsaturated acid. 5.8 g of this acid contained 2.4 g of carbon, 0.2 g of hydrogen and 3.2 g of oxygen.

i) How do you know that the acid contained only carbon, hydrogen and oxygen?

[1]

ii) Calculate the empirical formula of maleic acid.

Number of moles of carbon atoms = ................................

Number of moles of hydrogen atoms = ................................

Number of moles of oxygen atoms = ................................

The empirical formula is .................................................

[3]

iii) The mass of one mole of maleic acid is 116 g. What is its molecular formula?

[2]

iv) Maleic acid is dibasic. One mole of acid produces two moles of H⁺. Deduce its structural formula.

[2]

Alkenes are unsaturated hydrocarbons. They undergo addition reactions.

Two of the methods of making alkenes are cracking and the thermal decomposition of chloroalkanes.

i) Complete an equation for the cracking of the alkane, decane.

[2]

ii) Propene can be made by the thermal decomposition of chloropropane.

Describe how chloropropane can be made from propane.

reagents:  propane and ..............................

conditions ...................................................

[2]

The following alkenes are isomers.

i) Explain why they are isomers.

[2]

ii) Give the name and structural formula of another hydrocarbon that is isomeric with the above.

name ......................................................

structural formula

[2]

Give the name of the product when but-1-ene reacts with each of the following.

steam .........................................................
hydrogen ....................................................
bromine ......................................................

Alkenes can polymerise.

i) Deduce the name and structural formula of the monomer from the structure of the polymer.

 name of monomer .......................................................     structural formula

[2]

ii) Draw the structure of the polymer formed from the following monomer.

[2]

iii) Describe the pollution problems caused by the disposal of polymers in landfill sites and by burning.

landfill sites ..........................................................................................................

[2]

burning ..........................................................................................................

[1]

Butan-1-ol is used as a solvent for paints and varnishes, to make esters and as a fuel. Butan-1-ol can be manufactured from but-1-ene, which is made from petroleum.

Biobutanol is a fuel of the future. It can be made by the fermentation of almost any form of biomass - grain, straw, leaves etc.

But-1-ene can be obtained from alkanes such as decane, C₁₀H₂₂, by cracking.

i) Give the reaction conditions.

[2]

ii) Complete an equation for the cracking of decane, C₁₀H₂₂, to give but-1-ene.

C₁₀H₂₂ →

[2]

iii) Name the reagent that reacts with but-1-ene to form butan-1-ol.

[1]

i) Balance the equation for the complete combustion of butan-1-ol.

...... C₄H₉OH + ...... O₂ → ...... CO₂ + ...... H₂O

[2]

ii) Write a word equation for the preparation of the ester butyl methanoate.

[2]

The fermentation of biomass by bacteria produces a mixture of products which include biobutanol, propanol, hydrogen and propanoic acid.

i) Draw the structural formula of propanol and of propanoic acid. Show all the bonds.

[2]

ii) Why is it important to develop these fuels, such as biobutanol, as alternatives to petroleum?

[1]

How could you show that butanol made from petroleum and biobutanol are the same chemical?

The alkanes are generally unreactive. Their reactions include combustion, substitution and cracking.

The complete combustion of an alkane gives carbon dioxide and water.

 i) 10 cm³ of butane is mixed with 100 cm³ of oxygen, which is an excess. The mixture is ignited. What is the volume of unreacted oxygen left and what is the volume of carbon dioxide formed?

 C₄H₁₀ (g) + 6.5O₂ (g) → 4CO₂ (g) + 5H₂O (l)

 Volume of oxygen left = .................................................. cm³

 Volume of carbon dioxide formed = ................................. cm³

 [2]

ii) Why is the incomplete combustion of any alkane dangerous, particularly in an enclosed space?

 [2]

The equation for a substitution reaction of butane is given below.

 CH₃−CH₂−CH₂−CH₃ + Cl₂ → CH₃−CH₂−CH₂−CH₂−Cl + HCl

i) Name the organic product.

[1]

ii) This reaction does not need increased temperature or pressure.

 What is the essential reaction condition?

[1]

 iii) Write a different equation for a substitution reaction between butane and chlorine.

[1]

Alkenes are more reactive and industrially more useful than alkanes.

They are made by cracking alkanes.

i) Draw the structural formula of the polymer poly(propene).

 [2]

 ii) Give the structural formula and name of the alcohol formed when but-1-ene reacts with steam.

 name ..................................................

 [1]

 structural formula

 [1]

 iii) Deduce the structural formula of the product formed when propene reacts with hydrogen chloride.

 [1]

Esters, fats and polyesters all contain the ester linkage.

The structural formula of an ester is given below.

Name two chemicals that could be used to make this ester and draw their structural formulae. Show all bonds.

 names ................................ and ..............................

[2]

   structural formulae

[2]

i) Draw the structural formula of a polyester such as Terylene.

[2]

ii) Suggest a use for this polymer.

[1]