Crude oil and fuels

Question 1

Hydrocarbons

Answer 1

Any compound that contains carbon and hydrogen atoms only.

Question 2

What is the general formula for alkanes

Answer 2

CnH2n+2

Question 3

Alkanes

Answer 3

• Homologous series (organic compounds that
  react in a similar way)
• Saturated compounds (each carbon atom
  forms 4 single covalent bonds)

Question 4

What are the first 4 alkanes

Answer 4

Monkey - Methane
Eats - Ethane
Purple - Propane
Banana - Butane

Question 5

What are the properties of a shorter carbon chains?

Answer 5

• less viscous (more runny)
• more volatile (turn into gas at low temp)
• BP decreases
• more flammable

Question 6

Complete Combustion Equation

Answer 6

hydrocarbon + oxygen –> carbon dioxide + H2O

Question 7

Is complete combustion an exo or endo reaction

Answer 7

Exothermic reaction as it releases a lot of energy.

Question 8

What is the use of hydrocarbons

Answer 8

Used as fuels during complete combustion as it releases a lot of energy

Question 9

Fractional Distillation

Answer 9

1. The oil is heated until most of it has turned
   into gas which enters the fractionating
   column
2. There is a temperature gradient in the
   column, hot at the bottom and gets cooler as
   you go up.
3. The longer hydrocarbons have high BP so
   they condense back to liquid near the
   bottom. The shorter hydrocarbons have
   lower BP and condense back to liquid near
   the top.
   4.End up with crude oil mixture separated out
   into different fractions. Each fraction contains
   a mixture of hydrocarbons that all contains a
   similar number of carbon atoms.

Question 10

Crude oil

Answer 10

A mixture of lots of different hydrocarbons

Question 11

What is cracking?

Answer 11

Splitting up long-chain hydrocarbons (produced from fractional distillation) into short-chain hydrocarbons as they are flammable so good fuel and in demand.

Question 12

What reaction is cracking?

Answer 12

Thermal decomposition reaction

Question 13

What are the 2 types of cracking?

Answer 13

Catalytic and steam cracking

Question 14

Catalytic cracking

Answer 14

1. Heat up the long-chain hydrocarbon into gas
2. Then pass the hydrocarbon vapor over a hot
   powered aluminium oxide catalyst
3. The long chain molecules then split apart on
   the surface of the specks pf catalyst

Question 15

Steam cracking

Answer 15

1. heat up the long-chain hydrocarbon into gas
2. then mix the vapour with steam and heat
   them to very high temp

Question 16

Cracking equation

Answer 16

Long-chain alkane -> short-chain alkane + alkene