Crude Oil

Question 1

What is crude oil?

Answer 1

Crude Ouil is a complex mixture of hydrocarbons. A fossil fuel consisting of the remains of ancient biomass. It is a Finite resource as it cannot be replaced as it is used up.

Question 2

What is a hydrocarbon?

Answer 2

A compund made up exclusively of hydrogen and carbon atoms.

Question 3

What is a homologous series?

Answer 3

Series of compounds with same general formula, same functional groups and similar chemical properties

Question 4

Explain how fractional distillation of crude oil takes place

Answer 4

• Crude oil is heated and vaporised.
• Vapor rises up the fractionating column (tower).
• The column is hotter at the bottom and cooler at the top.
• Hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points.
• Large molecules, high boiling points
• collected at the bottom.
• Small molecules, low boiling points
• collected at the top.
• This gives fractions, which can be used in various ways

Question 5

What is cracking?

Answer 5

Whe large hydrocarbons are thermally broken down into smaller and useful molecules.

Question 6

What type of reaction is cracking?

Answer 6

Thermal decomposition

Question 7

What are the conditions for cracking?

Answer 7

Reactant heated to vapor, passed over a hot catalyst (catalytic cracking) or heated to vapor, mixed with steam and heated to high temperatures (steam cracking)

Question 8

How are the products of cracking used?

Answer 8

The products are alkanes and alkenes - used as polymers and for fuels

Question 9

As the molecules in hydrocarbons become bigger what changes occur?

Answer 9

• Boiling point increases: Large molecules are attracted to each other more strongly than smaller ones so more energy is neede to break these stronger intermolecular forces
• The liquids become less volatile: The bigger the hydrocarbon, the more slowly it evaporates at room temperature
• The liquids become more viscous is and flow less easily: liquids containing small hydrocarbons molecules are runny. Those containing large molecules flow less easily because of stronger forces of attraction between their molecules
• The liquids become darker in colour
• Bigger hydrocarbons do not burn as easily as smaller ones. This limits the use of the bigger ones as fuels

Question 10

Name all the fractions in crude oil in order

Answer 10

Question 11

Give an example of a catalyst used in cracking

Answer 11

Aluminium oxide

Question 12

How is incomplete combustion caused?

Answer 12

If there isn’t enough air for

Question 13

Why is carbon monoxide dangerous?

Question 14

How is Acid rain formed?

Answer 14

Acid rain is formed when water and oxygen in the atmosphere react with soulful dioxide to produce sulfuric acid (H)

Question 15

Why is Acid rain a problem?

Answer 15

• Limestone buildings and statues are damaged by acid rain
• Acid rain reduces growth of trees and growth or kills trees and crops
• Acid rain lowers the pH of river water killing fish