Organic Chemisty

Question 1

What’s the chemical test for Alkenes?

Answer 1

Add Bromine water to sample. If present, it’s colourless

Question 2

Name the types of cracking

Answer 2

Steam cracking:
Vaporised hydrocarbons mixed with steam
Very high temp over 800 degrees

Catalytic cracking:
Vaporised hydrocarbons pass over a hot catalyst
High temps reaching 550 degrees

Question 3

Name the types of cracking

Answer 3

Steam cracking:
Vaporised hydrocarbons mixed with steam
Very high temp over 800 degrees

Catalytic cracking:
Vaporised hydrocarbons pass over a hot catalyst
High temps reaching 550 degrees

Question 4

3 uses of Alkene

Answer 4

Fuel
- Starting point for making polymers, e.g. plastics, polythene, polystyrene
- Starting materials for lubricants

Question 5

Alkene structure?

Answer 5

• One Double covelant bond (C=C)
• We say they are unsaturated
• This makes them more reactive then Alkanes

Question 6

What is cracking?

Answer 6

When a longer Alkene is formed into a shorter alkane + Alkene

Question 7

What are the first four alkanes?

Answer 7

1) Methane
2) Ethane
3) Propane
4) Butane

Question 8

What are the 6 stages of fractional distillation?

Answer 8

1) Crude oil is heated in a furnace
2) The gas mixture then starts to vaporise and rise when it enters the column
3) The temperature varies from being hot at the bottom and cool at the top
4) Once they (hydrocarbon gases) reach their boiling point the bonds start to break
5) Then the shorter chain molecules rise resulting in them condensing
6) The crude oil has been separated into different fractions.

Question 9

What is a fraction?

Answer 9

Molecules with similar chain lengths

Question 10

Structue of Methane, Propane, Ethane and Butane

Answer 10

Methane = CH4
Ethane = C2H6
Propane = C3H8
Butane = C4H10

Question 11

Memorise

Answer 11

The longer the carbon chain length, the higher the boiling point, the increase in viscosity but decrease in flammability.

Question 12

What does viscosity mean?

Answer 12

How easily a substance flows

E.g. honey is very viscous, whereas water is less viscous

Question 13

What does “saturated” mean?

Answer 13

An Alkene is when no more atoms can be added because it has the maximum number of bonds.

Question 14

What is a hydrocarbon?

Answer 14

A compound that only consists of hydrogen and carbon atoms

Question 15

How is crude oil formed?

Answer 15

By dead plants (mostly plankton) and animals which are buried under sand/sediment. Over millions of years they form into Crude Oil from intense pressure

Question 16

What is the Alkanes general formula?

Answer 16

Cn + H2n+2

n = being number of atoms

Question 17

What is the Alkene general formula?

Answer 17

Cn + H2n

n = number of atoms

Question 18

Why is electron microscopes better than light microscopes?

Answer 18

They have a higher magnification and resolution

Question 19

What are alkanes?

Answer 19

Hydrocarbons with single carbon to carbon bonds.

C-C bonds

Question 20

What is organic chemistry?

Answer 20

A carbon based compounds

Question 21

What is a mixture?

Answer 21

A combination of elements that can be separated meaning it isn’t chemically combined

Question 22

What is a compound?

Answer 22

A combination of elements that are chemically bonded

Question 23

What is an Alkene?

Answer 23

Hydrocarbons with double carbon to carbon bonds.

C=C bonds