Organic Chemistry

Question 1

What is crude oil?

Answer 1

A finite resource and mixture of many hydrocarbons found in rocks.

Question 2

What is complete combustion?

Answer 2

An oxidation reaction that occurs when a fuel reacts with plenty oxygen.
[e.g. hydrocarbon + oxygen ⟶ carbon dioxide + water]

Question 3

Why are hydrocarbon use as fuels?

Answer 3

Their combustion releases a lot of energy.

Question 4

What happens as the length of hydrocarbon chain increases?

Answer 4

> the boiling increases.
the viscosity increases.
the flammability decreases.

Question 5

What is fractional distillation?

Answer 5

A process used to separate the hydrocarbons in crude oil into fractions according to they boiling points.

Question 6

What are alkanes?

Answer 6

The simplest type of hydrocarbon, containing only single covalent bonds as they’re saturated.

Question 7

What is the number of atoms and formula, structure of methane?

Answer 7

NUMBER OF CARBON ATOMS ⟶ 1.
FORMULA ⟶ CH₄.
STRUCTURE 
↳   H
        |
H ⎯  C ⎯ H
        |
       H

Question 8

What is the number of atoms and formula, structure of ethane?

Answer 8

NUMBER OF CARBON ATOMS ⟶ 2.
FORMULA ⟶ C₂H₆.
STRUCTURE
↳    H   H
         |     |
 H ⎯  C ⎯ C ⎯ H
         |     |
        H   H

Question 9

What is the number of atoms and formula, structure of propane?

Answer 9

NUMBER OF ATOMS ⟶ 3.
FORMULA ⟶ C₃H₈.
STRUCTURE
↳    H   H   H
         |     |     |
 H ⎯  C ⎯ C ⎯ C ⎯ H
         |     |     |
        H   H   H

Question 10

What is the number of atoms and formula, structure of butane?

Answer 10

NUMBER OF ATOMS ⟶ 4.
FORMULA ⟶ C₄H₁₀.
STRUCTURE
↳   H   H   H   H
        |     |     |     |
H ⎯  C ⎯ C ⎯ C ⎯ C ⎯ H
        |     |     |     |
       H   H   H   H

Question 11

What is meant by the term cracking in chemistry?

Answer 11

Breaks down long-chain hydrocarbons into shorter more useful ones.
[long-chain alkane ⟶ shorter-chain alkane + alkane]

Question 12

Long-chain hydrocarbons are vaporised by heating. What are the two methods of cracking?

Answer 12

> catalysts cracking.

> steam cracking.

Question 13

What happens during catalysts cracking?

Answer 13

Hydrocarbon vapour is passed over a hot powdered aluminium catalyst.

Question 14

What happens during steam cracking?

Answer 14

Hydrocarbon vapour is mixed with steam and heated to a very high temperature.

Question 15

What is crude oil made of?

Answer 15

It is the remains of an ancient biomass consisting mainly of plankton that was buried in the mud.

Question 16

What are hydrocarbons?

Answer 16

Molecules made up of hydrogen and carbon atoms only.

Question 17

What is the formula for the homologous series of alkenes?

Answer 17

CnH₂n+2

Question 18

What are the first four members of the alkanes?

Answer 18

> methane.
ethane.
propane.
butane.

Question 19

How can crude oil be separated?

Answer 19

Through fractional distillation.

Question 20

What happens when crude oil goes through the process of fractional distillation?

Answer 20

Crude oil is heated up to evaporate into vapour and as the vapours rise up the column they undergo condensation at the molecules boiling point and turn back into a liquid fraction to be collected.

Question 21

What happens as the hydrocarbon chain gets longer?

Answer 21

> boiling point increases.
viscosity increases.
flammability decreases.

Question 22

What are some examples of the use of crude oil in everyday life?

Answer 22

> petrol.
> diesel.
> kerosene.
> heavy fuel oil.
> liquefied petroleum gases.

Question 23

What does the complete combustion of hydrocarbons produce?

Answer 23

Carbon dioxide and water.

Question 24

What is the equation for the complete combustion of methane?

Answer 24

CH₄+2O₂⟶CO₂+2H₂O