Question
Coal gas is made by heating coal in the absence of air. The list shows the main gases present in coal gas.
carbon dioxide
carbon monoxide
ethene
hydrogen
methane
nitrogen
(a) (i) Which one of these gases is an alkane?……………………………………………………………………………………………………………………… [1]
(ii) Draw the structure of a molecule of ethene. Show all of the atoms and all of the bonds.[1]
(iii) Describe how aqueous bromine can be used to tell the difference between methane andethene.……………………………………………………………………………………………………………………… [2]
(b) Ethene molecules react with each other to form poly(ethene).
(i) What is the name given to this type of chemical reaction?……………………………………………………………………………………………………………………… [1]
(ii) Which one of the following words describes the ethene molecules in this reaction?
Draw a circle around the correct answer.
elements mixtures monomers polymers[1]
(iii) Poly(ethene) is a non-biodegradable plastic.
What is meant by the term non-biodegradable?……………………………………………………………………………………………………………………… [1]
(iv) Describe one pollution problem caused by non-biodegradable plastics.……………………………………………………………………………………………………………………… [1]
(c) Ethanol can be made from ethene and one other reactant.
● Name the other reactant.………………………………………………………………………………………………………………………………….
● State the conditions needed to make ethanol from ethene.………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………….[3][Total: 11]
▶️Answer/Explanation
Ans:
(a)(i) methane
(a)(ii)
(a)(iii) with methane (aqueous) bromine remains orange (1)
with ethene (aqueous) bromine decolourised (1)
(b)(i) polymerisation / addition
(b)(ii) monomers
(b)(iii) cannot be decomposed by organisms / cannot be broken down by bacteria / cannot be broken down by fungi
(b)(iv) gets stuck in gullets of birds / gets stuck in gullets of animals / blocks drains
(c) steam (1)
high temperature (1)
catalyst (1)
Question
(a) The structures of four organic compounds, P, Q, R and S, are shown.
Answer the following questions about these structures.
Each structure may be used once, more than once or not at all.
(i) State which structure, P, Q, R or S, has a carboxylic acid functional group.[1]
(ii) State which structure, P, Q, R or S, is in the same homologous series as ethane.[1]
(iii) State which structure, P, Q, R or S, decolourises aqueous bromine.[1]
(iv) Deduce the molecular formula of structure Q to show the number of carbon, hydrogen and oxygen atoms.[1]
(b) Structure S is produced by cracking petroleum fractions.
(i) Complete the sentence using a word from the list.
acids alkenes alcohols nitrogen
During cracking, long-chain alkanes are converted to shorter chain alkanes and[1]
(ii) Cracking is an example of thermal decomposition.
State the meaning of the term thermal decomposition.[2]
(c) Link each petroleum fraction on the left to its use on the right.
The first one has been done for you.
Answer/Explanation
Ans:
(a)(i) Q
(a)(ii) S
(a)(iii) R
(a)(iv) C4H8O2
(b)(i) alkenes
(b)(ii) breakdown of a compound (1)
using heat / by heat (1)
(c) naphtha → making chemicals
lubricating fraction → waxes and polishes
kerosene → jet fuel
all 3 correct (2)
1 or 2 correct (1)
Question
(a) The structures of four organic compounds, C, D, E and F, are shown.
Answer the following questions about these compounds.
Each compound may be used once, more than once or not at all.
State which compound, C, D, E or F:
(i) decolourises aqueous bromine [1]
(ii) is an alcohol [1]
(iii) is unsaturated [1]
(iv) is in the same homologous series as ethane. [1]
(b) Petroleum is a mixture of hydrocarbons which can be separated into fractions with different boiling points.
Name the method used to separate these fractions.[1]
(c) Complete the table to show the name and uses of some petroleum fractions.[3]
(d) Some hydrocarbons are formed by the process of cracking.
(i) State the meaning of the term cracking.[2]
(ii) Describe the conditions needed for cracking.[2] [Total: 12]
Answer/Explanation
Ans:
(a)(i) C
(a)(ii) D
(a)(iii) C
(a)(iv) E
(b) (fractional) distillation
(c) refinery gas: heating / cooking (1)
gasoline: fuel for cars / fuel for vehicles (1)
waxes: lubricating (fraction) (1)
(d)(i) breakdown / decomposition of hydrocarbons (1)
idea of long chain hydrocarbons being converted to short chain hydrocarbons (1)
(d)(ii) heat / thermal (decomposition) / high temperature (1)
catalyst (1)