Chemistry Topic 7- Hydrocarbons + Fractional Distillation

Question 1

What is a hydrocarbon?

Answer 1

It is ANY compound that is formed from carbon (C) and hydrogen (H) atoms only

Question 2

Do alkanes have single or double bonds?

Answer 2

Single (C-C)

Question 3

What is their general formula?

Answer 3

C. H

n. 2n+2

Question 4

What is the name of the first 4 alkanes and their formula?

Answer 4

1. Methane (CH4)
2. Ethane (C2H6)
3. Propane (C3H8)
4. Butane (C4H10)

Question 5

*the alkanes are a homologous series

What does this mean?

*alkanes are saturated compounds

What does this mean?

Answer 5

1. That they are a group of organic compound that react in a similar way
2. That each carbon atom forms 4 single covalent bonds

Question 6

What properties occur as the carbon chain gets shorter?

Answer 6

1. Less viscous (gloopy)
2. More volatile (lower boiling point)
3. More flammable

Question 7

How do the properties of hydrocarbon affect how they’re used for fuels?

Answer 7

For example, short chain hydrocarbons with lower boiling points are used as ‘bottled gases’- stored under pressure as liquids in bottles

Question 8

What is the equation for complete combustion of a hydrocarbon?

Answer 8

Hydrocarbon + oxygen —> carbon dioxide + water

Question 9

*hydrocarbon + oxygen —> carbon dioxide + water

What is oxidised during this reaction?

What does oxidation mean?

Answer 9

1. Both the carbon and hydrogen from the hydrocarbon

2. Oxidation is the gain of oxygen

Question 10

Why are hydrocarbons used as fuels?

Answer 10

Because of the amount of energy released when they combust completely

Question 11

How is crude oil made?

Answer 11

• crude oil is a fossil fuel
• its formed when the remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud on the sea bed
• over millions of years, with high temperature and pressure, the remains turn to crude oil
• the crude oil can be drilled up from the rocks where its found

Question 12

Why is fractional distillation used?

Answer 12

To separate hydrocarbon fractions

Question 13

What is crude oil a mixture of?

Answer 13

Lots of different hydrocarbons, most of which are alkanes

Question 14

What is made at each fraction (top to bottom)?

• include approximate number of carbons in the hydrocarbons in that fraction
• include what they’re used for

Answer 14

1. LPG (Liquefied Petroleum Gas) it contains mostly propane and butane [3]
2. Petrol- cars [8]
3. Kerosene- planes [15]
4. Diesel Oil- trucks [20]
5. Heavy Fuel Oil- heating oil, fuel oil or lubricating oil [40]