hydrocarbons (topic 7)

Question 1

state the name of the hydrocarbon in the diagram below

Answer 1

propane

Question 2

draw the structure of butene

Answer 2

Question 3

explain what is meant by the term saturated hydrocarbon (2)

Answer 3

• hydrocarbon because it only contains hydrogen and carbon
• saturated because it has no double bonds

Question 3

state the general formula for alkanes

Answer 3

Question 3

propene (C3H6) is an alkene, describe the test that can be done to distinguish between a sample of propane and a sample of propene (3)

Answer 3

• mix sample with bromine water
• bromine water is orange
• when mixed with an alkene, it turns colourless
• when mixed with an alkane, no colour change occurs

Question 3

state the name of the industrial process used to separate crude oil into fractions and outline the process (4)

Answer 3

• fractional distillation
• crude oil is heated/vapourised
• fractionating column is cooler at the top than at the bottom
• fractions have different boiling points so condense at different heights

Question 4

bitumen is a fraction that is removed near the base of the fractioning column, state one use of bitumen (2)

Answer 4

• used to surface roads
• bitumen can be cracked into shorter chain hydrocarbons

Question 5

describe the trend shown by the graph (1)

Answer 5

as the length of alkane increases, the boiling point increases

Question 6

a long chain hydrocarbon has the chemical formula C14H30, when it undergoes cracking it splits into decane and another hydrocarbon, X, write a chemical equation to show this reaction and state the name given to the other hydrocarbon, X

Answer 6

butene

Question 7

describe the conditions required to crack long chain hydrocarbons into shorter chain hydrocarbons (2)

Answer 7

• high temperature
• in the presence of steam or a catalyst

Question 8

Answer 8

Question 9

name the fraction that is used as aviation fuel

Answer 9

kerosene

Question 10

state two differences, other than boiling point, between the properties of kerosene and bitumen (2)

Answer 10

• kerosene is more flammable/volatile than bitumen
• kerosene has a lower melting point than bitumen
• kerosene has a lower density than bitumen
• kerosene is less viscous than bitumen

Question 11

when the fraction C7H16 is combusted, it reacts with oxygen in the air to form carbon dioxide and water, write a balanced chemical equation for this reaction

Answer 11

Question 12

Answer 12

Question 13

explain what is meant by the term unsaturated (1)

Answer 13

contains a double bond between two carbon atoms

Question 14

describe a test that can be done to test if a hydrocarbon is saturated or unsaturated (2)

Answer 14

• place small sample of hydrocarbon in a test tube with bromine water
• colour will change to colourless if the hydrocarbon is unsaturated
• or no colour change if saturated

Question 15

ethene reacts with steam in the presence of a catalyst to form an alcohol, explain the role of a catalyst in this reaction (2)

Answer 15

• increases the rate of reaction without changing the products produced
• by providing an alternative reaction pathway
• with a lower activation energy

Question 16

Answer 16

Question 17

state the name of the alcohol formed in this reaction, reaction between ethene and steam

Answer 17

ethanol

Question 18

propene reacts with hydrogen to form a saturated hydrocarbon, write the balanced symbol equation for this reaction

Answer 18

Question 19

state the name of the homologous series that C3H8 belongs to

Answer 19

alkanes

Question 20

Answer 20

hydration

Question 21

Answer 21

C5H11

Question 22

test for a unsaturated hydrocarbon

Answer 22

bromine water changes to colourless

Question 23

write a balanced symbol equation for the complete combustion of methane

Answer 23

Question 24

test for a saturated hydrocarbon results

Answer 24

bromine water stays orange