Formulae, Functional Groups & Terminology (Cambridge O Level Chemistry)

The structures of six organic compounds are shown.

Give the name of F.

Identify two of the compounds that are members of the same homologous series.

Give the general formula of this homologous series.

compounds ..................................................

general formula ..................................................

Which two compounds are isomers of each other?

Explain why they are isomers.

compounds ........................................................................

explanation ........................................................................

Explain why B is an unsaturated hydrocarbon.

Describe how D is manufactured from B. Give a chemical equation for the reaction.

Compound A forms an addition polymer.

Draw two repeat units of the addition polymer formed from A.

A hydrocarbon has the following structural formula.

Alkenes can be made from alkanes by cracking.

Alkenes are used in polymerisation reactions and addition reactions.

The alcohols form a homologous series. The first five members are given in the table below.

State three characteristics of a homologous series other than the variation of physical properties down the series.

The following alcohols are isomers.

Alcohols can be made by fermentation and from petroleum.

The alcohols form a homologous series.

Give three characteristics of a homologous series.

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

Copper(II) oxide can oxidise butanol to liquid X, whose pH is 4.

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.

Methanoic acid is the first member of the homologous series of carboxylic acids.

Give two general characteristics of a homologous series.

In some areas when water is boiled, the inside of kettles become coated with a layer of calcium carbonate. This can be removed by adding methanoic acid.

Give the name, molecular formula and empirical formula of the fourth acid in this series.

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.

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

Alkynes and alkenes are homologous series of unsaturated hydrocarbons.
All alkynes contain a C≡C triple bond.

Complete Table 10.1 showing information about the first three alkynes.

Table 10.1

formula
structure
names	ethyne		but-1-yne

Compounds in the same homologous series have the same general formula.

Give two other characteristics of members of a homologous series.

Deduce the general formula of alkynes.

Use the information from Table 10.1 to help you.

Alkynes are unsaturated.
Describe a test for unsaturation.
test   ........................

result ........................ 

Ethene and but-2-ene are alkenes.
Draw the displayed formula of but-2-ene.

Draw a dot-and-cross diagram to show a molecule of ethene, CH₂=CH₂.
Show outer shell electrons only.

Propane reacts with chlorine in a photochemical reaction as shown.

Draw two structural isomers of compounds with the formula C₃H₇Cl.
Show all of the atoms and all of the bonds.

There are three functional groups in compound A.

Name the homologous series of compounds that contains the following structures.

C=C       ...............................
–OH       ..............................
–COOH ...............................

Compound A can be used as a single monomer to produce two different polymers.

Draw one repeat unit of the addition polymer formed from compound A.

The structure of compound S is shown.

Draw a circle around the carboxylic acid functional group in this structure.

How many different types of atom are shown in this structure?

Ethanol can be converted into ethene by passing ethanol vapour over a catalyst of aluminium oxide.

Draw the structure of a molecule of ethanol. Show all of the atoms and all of the bonds.

The structure of myrcene is shown.

Deduce the formula of myrcene to show the number of atoms of carbon and hydrogen.

Myrcene is an unsaturated hydrocarbon.

Describe a chemical test to distinguish between a saturated and an unsaturated hydrocarbon.

test ...................................
observations with saturated hydrocarbon .............................................
observations with unsaturated hydrocarbon .........................................

Butane is a saturated hydrocarbon.

To which homologous series does butane belong?

Draw a circle around the correct answer.

alcohol                    alkane                   alkene                   carboxylic acid

Choose from the following compounds to answer the questions.

Each compound may be used once, more than once or not at all.

State which compound:

State which two compounds in aqueous solution turn blue litmus red.

Fig. 12.1 shows the alcohols ethanol and butan-1-ol.

Fig. 12.1

Describe the manufacture of ethanol from ethene.

Ethanol is used as a fuel.

[1]

[2]

Ethanol is oxidized to form ethanoic acid. State the name of a reagent that is used for this oxidation.

Draw the displayed formula of a different alcohol that is an isomer of butan-1-ol.

Butan-1-ol is heated with concentrated sulfuric acid which acts as a catalyst. But-1-ene and one other compound are formed.

[1]

[1]

But-2-ene, CH₃CH=CHCH₃, is polymerised to give poly(but-2-ene).

[1]

[1]

Alkanes and alkenes are examples of hydrocarbons.

[1]

A compound X contains carbon, hydrogen and oxygen only.

X contains 54.54% of carbon by mass, 9.09% of hydrogen by mass and 36.37% of oxygen by mass.

An ester has the molecular formula C₃H₆O₂.

Name and give the structural formulae of two esters with the molecular formula C₃H₆O₂.

Name the ester produced from the reaction of propanoic acid and methanol.

A polyester is represented by the structure shown.

[1]

[1]

[2]

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

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

Carboxylic acids can be made by the oxidation of alcohols.

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

The salts of this acid are called propanoates.

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 temperature.

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

The alcohols form a homologous series. The first member is methanol and the fourth is butanol.

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

The structural formula of the fifth member, pentan-1-ol, is drawn below.

• reacts with an excess of oxygen,

• is dehydrated to form an alkene,

• is oxidised by acidified potassium dichromate(VI).

Butane is oxidised to a mixture of carboxylic acids by oxygen in the presence of a catalyst. The acids formed are methanoic acid, ethanoic acid and propanoic acid – the first three members of the carboxylic acid homologous series.

Carboxylic acids react with alcohols to form esters. Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate, CH₃COOCH₂CH₃.

Butane is an alkane. It has the following structural formula

The equation for the complete combustion of butane is given below. Insert the two missing volumes.

Butane reacts with chlorine to form two isomers of chlorobutane.

One of the chlorobutanes reacts with sodium hydroxide to form butan-1-ol. Butan-1-ol can be oxidised to a carboxylic acid.

The table shows some information about aldehydes.

Complete the table.

Deduce the general formula of aldehydes.

The structural formula of ethanal is shown.

The C=O group in aldehydes is at the end of the carbon chain.
This is a reactive part of the molecule.

What is the name given to the reactive part of any organic molecule?

Propanone belongs to a homologous series called ketones. Ketones have the same C=O group as aldehydes but the C=O group is not at the end of the carbon chain. Propanone has the same molecular formula as propanal, C₃H₆O.

What term is used to describe molecules with different structures but with the same molecular formula?

Suggest the structure of propanone, C₃H₆O. Show all of the atoms and all of the bonds.