C9 - Crude Oil and Fuels

Question 1

What is crude oil?

Answer 1

Crude oil is a resource found underground, made up of mostly compounds made up of hydrogen and carbon atoms - hydrocarbons.

Additionally, many of these hydrocarbons are saturated, and only have single bonds between carbon atoms. These hydrocarbons are called alkanes, and have a general formula of CnH(2n+2)

Question 2

What happens as hydrocarbons get larger?

Answer 2

• Boiling point increases
• Volatility decreases
• Viscosity increases (thicker)
• Flammability decreases.

Question 3

What is fractional distillation?

Answer 3

The method used to seperate the chemicals in crude oil.

Oil is vaporised at the bottom of a tower. Then, as the vapor rises towards the top, the tower gets cooler and cooler, until each individual chemical hits its boiling point and condenses. The condensed chemical is then run off into individual containers.

Question 4

What happens when you burn a hydrocarbon (complete combustion)?

Answer 4

The carbon and oxygen become oxidized, forming carbon dioxide and water.

Question 5

How do you test for the gases burning a hydrocarbon produced?

Answer 5

• Bubble into limewater - goes cloudy - carbon dioxide present.
• Cobalt chloride paper - turns pink - water present.

Question 6

What happens when you burn a hydrocarbon (incomplete combustion)?

Answer 6

Carbon monoxide is produced as a side product.

Question 7

What is “cracking” hydrocarbons?

Answer 7

The breaking up of large hydrocarbon molecules into smaller molecules, by passing it over a hot catalyst or mixing it with hot steam.

-ene molecules are created, which have double bonds between a set of carbon atoms.

Question 8

How do you test for alkenes?

Answer 8

Bubble product through orange bromine water. If it turns colourless, alkenes are present.