Crude oil and fuels

Question 1

Where does crude oil come from?

What is it?

Answer 1

Ancient biomass (dead plants and animals from long ago) found in rocks
A mixture of a very large number of compounds

Question 2

Define a mixture

What is distillation of a mixture?

Answer 2

Two or more elements or compounds not chemically combined together, where the chemical properties of each substance is not changed
A physical method used to separate these substances from one another

Question 3

What is crude oil mainly made up of?

Answer 3

Compounds consisting of molecules made up of carbon and hydrogen atoms (hydrocarbons), most of which are saturated hydrocarbons called alkanes

Question 4

What is the general formula for alkanes?

Answer 4

CnH2n+2

Question 5

How many carbon atoms do methane, ethane, propane and butane have?
What is a way of remembering the order?

Answer 5

1, 2, 3, 4 respectively

Monkeys Eat Peanut Butter

Question 6

In a displayed structure, what does a – represent?

How many bonds does each carbon atom have?

Answer 6

A covalent bond

4

Question 7

What is a fraction?

Answer 7

When the many hydrocarbons in crude oil are separated into groups of molecules with similar numbers of carbon atoms

Question 8

What is fractional distillation?

Answer 8

Evaporating the crude oil and allowing it to condense at a number of different temperatures into fractions

Question 9

How does the size of hydrocarbons influence their properties?

Answer 9

The bigger they are, the higher the boiling point, the more viscous they are, and the less flammable they are

Question 10

What do most fuels contain?

What gases and other substances might be released into the atmosphere when a fuel burns?

Answer 10

Carbon and/or hydrogen and maybe some sulphur (especially coal)
Carbon dioxide (CO2), water vapour (H2O), carbon monoxide (CO), sulphur dioxide (SO2), oxides of nitrogen formed at high temperatures (NOx), and solid particulates (including soot/carbon and unburnt fuels)

Question 11

Give the equation for incomplete combustion of methane (unbalanced)

Answer 11

CH4 + O2 –> CO + H2O

Question 12

Other than gases being released, what happens during combustion of hydrocarbon fuels?

Answer 12

Energy is released and carbon and hydrogen in the fuels are oxidised

Question 13

What are the environmental impacts of burning hydrocarbon fuels?

Answer 13

Sulphur dioxide and nitrogen oxides cause acid rain
Carbon dioxide (and water) cause global warming
Solid particulates cause global dimming

Question 14

How can sulphur dioxide emissions be reduced?

Answer 14

Sulphur can be removed from the fuel before combustion, or sulphur dioxide can be removed afterwards, such as with chemical scrubbers on power stations

Question 15

What are biofuels?

Answer 15

Fuels made from plant materials, such as biodiesel and ethanol

Question 16

What are the positives and negatives for using biofuels?

Answer 16

P: Often carbon neutral, don’t release as much particulates, biodiesel is biodegradable, biodiesel doesn’t come with transportation drawbacks, biodiesel keeps engines clean because it is a good solvent
N: The materials used sell for much more than food products, so farmers in poor countries grow these cash crops instead of feeding their country leads to food poverty; biodiesel produces more nitrogen oxides than crude oil fuels; biodiesel leads to deforestation

Question 17

What are the positives and negatives of using hydrogen as a fuel?

Answer 17

P: Limitless supply of hydrogen, the only product of combustion is water
N: Hydrogen is stored in fuel cells, which are extremely expensive