Organic chemistry

Question 1

What is crude oil?

Answer 1

A mixture of molecules called HYDROCARBONS.

Question 2

What are hydrocarbons?

Answer 2

They are molecules made up of HYDROGEN and CARBON atoms only.

Question 3

What are alkanes?

Answer 3

Alkanes are SATURATED HYDROCARBONS containing SINGLE BONDS.

Question 4

What are the first 5 alkanes?

Answer 4

1. Methane
2. Ethane
3. Propane
4. Butane
5. Hexane

Question 5

What is the general formula for alkanes?

Answer 5

CnH2n+2

Question 6

What is the formula for butane?

Answer 6

C..H…

..4…10.

Question 7

What is meant by viscosity?

Answer 7

Tells us the THICCNESS of a fluid.

Question 8

What happens to the viscosity as the size of the hydrocarbon molecules increases.

Answer 8

The molecules get MORE viscous.

Question 9

What happens to the flammability as the size of the hydrocarbon molecules increases.

Answer 9

The molecules get LESS flammable.

Question 10

What happens to the boiling point as the size of the hydrocarbon molecules increases.

Answer 10

The molecules have HIGHER boiling points.

Question 11

Why are alkanes methane, ethane, propane and butane gases at room temperature?

Answer 11

Because they all have BOILING POINTS which are LOWER than room temperature.

Question 12

When do hydrocarbon fuels release energy?

Answer 12

When COMBUSTED (burned).

Question 13

Describe the steps involved in the fractional distillation of crude oil. (3)

Answer 13

1. HEAT crude oil to VAPORISE.
2. Vapours CONDENSE.
3. At different TEMPERATURES (lower bpt at top higher bpt at bottom).

Question 14

Propane is an alkane with 3 carbon atoms. Draw the structure of propane.

Answer 14

…….H…H….H…………

……..I…..I……I………….

H - C - C - C - H

……..I…..I……I…………..

…….H…H….H………….

Question 15

What is cracking?

Answer 15

It is when a LARGER HYDROCARBON molecule is broken down to produce SMALLER more USEFUL molecules.

Question 16

Name 2 ways in which cracking can be carried out?

Answer 16

1. -Catalytic cracking
2. Steam cracking

Question 17

What are alkenes?

Answer 17

Alkenes are UNSATURATED hydrocarbons containing a DOUBLE BOND.

Question 18

How do we test for alkenes?

Answer 18

• We use BROMINE WATER (orange).
• If we shake our alkene with bromine water, then bromine water turns COLOURLESS.

Question 19

What is key about balancing equations for cracking?

Answer 19

The number of C and H atoms on the right hand side must be the SAME as the left hand side.

Question 20

What is the general formula for alkenes?

Answer 20

CnH2n