SC22 Hydrocarbons

Question 1

List the names and formulae for the first 4 members of the alkane homologous series

Answer 1

Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10

Question 2

Define saturated hydrocarbons

Answer 2

All bonds that can be formed have been formed

Question 3

Define unsaturated hydrocarbons

Answer 3

Not all bonds have been formed, so they can make more bonds

Question 4

Define functional group (and in alkenes)

Answer 4

A functional group is a group of atoms that determine how a molecule reacts - in alkenes, the functional group is C=C

Question 5

What are the differences between but-1-ene and but-2-ene?

Answer 5

The functional group C=C is in a different arrangement within the atom in but-1-ene and but-2-ene

Question 6

Define an addition reaction

Answer 6

A type of reaction where two smaller molecules react to make a single, larger molecule and no others

Question 7

Chemical test to distinguish between alkanes and alkenes

Answer 7

Bromine water:
Alkenes will decolourise bromine water
Alkanes will NOT decolourise bromine water

Question 8

Why are the products of complete combustion CO2 and water?

Answer 8

Hydrocarbons are made of carbon and hydrogen. Therefore the products are made from carbon and hydrogen just rearranged into carbon dioxide and water

Question 9

Define isomer

Answer 9

Different versions of the same molecule, They have the same molecular formula, but the functional group is in a different place

Question 10

What colour is bromine water?

Answer 10

Pale brown/orange colour