Alkanes

Question 1

What is organic chemistry about?

Answer 1

Compounds that contain carbon

Question 2

Why is carbon ideal for forming compounds?

Answer 2

Can form 4 single covalent bonds

Question 3

What is a hydrocarbon ?

Answer 3

Any compound formed by carbon and hydrogen only

Question 4

Is butanol a hydrocarbon?

Answer 4

No- contains oxygen aswell

Question 5

Name the first 4 alkanes?

Answer 5

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

Question 6

Why are the alkanes a “homologous series”?

Answer 6

They have similar properties and all react in a similar way

Question 7

The alkanes have a general formula because they are a homologous series -what is it?

Answer 7

CnH2n+2

Question 8

Why are alkanes saturated compounds?

Answer 8

Every atom has 4 single covalent bonds

Question 9

How does the flammability of an alkane vary with chain length?

Answer 9

As the chain length increases, the alkanes become less flammable

Question 10

How does the viscosity of alkanes vary with chain length?

Answer 10

The longer the chain, the more viscous (thick and gloopy) the alkane is

Question 11

How does the volatility of alkanes vary with chain length?

Answer 11

As the chain length increases, the alkane becomes less volatile (evaporates less easily)

Question 12

How do the boiling points vary with increased chain length?

Answer 12

Boiling point increases

Question 13

What are hydrocarbon’s main use?

Answer 13

For fuel

Question 14

What do hydrocarbons release lots of when burnt with oxygen? (Combustion)

Answer 14

Energy

Question 15

What occurs when a hydrocarbon burns with ENOUGH oxygen?

Answer 15

Complete combustion

Question 16

Finish the Equation:

Hydrocarbon + Oxygen ——>

Answer 16

Carbon Dioxide + Water

Question 17

What two kinds of reaction is complete combustion?

Answer 17

1) Exothermic
2) Oxidation

Question 18

What do the properties of alkanes depend on?

Answer 18

Chain length

Question 19

How is crude oil separated into its different compounds?

Answer 19

Fractional distillation

Question 20

What is crude oil?

Answer 20

A mixture of different hydrocarbons

Question 21

How is crude oil formed?

Answer 21

Naturally from condensed animal and plant remains condensed into rocks under high pressure

Question 22

How is crude oil retrieved?

Answer 22

By drilling into rocks and sucking it up to the surface

Question 23

What is meant by crude oil being a finite resource?

Answer 23

It will run out

Question 24

What is STEP 1 of fractional distillation of crude oil?

Answer 24

1) feed the oil into a chamber and heat until most of it is gaseous

Question 25

What is STEP 2 of fractional distillation of crude oil?

Answer 25

2) Pass the gaseous mixture into a fractionating column

Question 26

Where is the fractionating column hottest?

Answer 26

The bottom

Question 27

What happens when a hydrocarbon reaches a region lower in temperature than it’s boiling point?

Answer 27

Is condenses

Question 28

Which two hydrocarbons are longest on chain and therefore condense furthest down the column?

Answer 28

1) Bitumen 2) Heavy fuel oil

Question 29

Which 3 hydrocarbons are shortest in length and therefore condense furthest up the column?

Answer 29

3)Diesel 2) Kerosene 1)Petrol

Question 30

Which hydrocarbon stays a gas throughout the column?

Answer 30

Liquified petroleum gas

Question 31

Why are short hydrocarbons the best fuels?

Answer 31

They are the most flammable

Question 32

In what 4 ways are the products of fractional distillation of crude oil used as feedstock in the petrochemical industry?

Answer 32

1) solvents 2) Lubricants 3) Polymers 4) Detergents

Question 33

What kind of reaction is cracking?

Answer 33

Thermal decomposition

Question 34

Why is cracking used?

Answer 34

To separate long chain hydrocarbons into shorter hydrocarbons

Question 35

What is the first step to cracking?

Answer 35

1) heat and vaporise the hydrocarbon

Question 36

What happens in catalytic cracking?

Answer 36

The vapour is poured over hot, powdered aluminium oxide which the hydrocarbons splits into two on when it comes into contact with it.

Question 37

What happens in steam cracking?

Answer 37

The vapour is mixed with steam and heated to a very high temperature, which causes the hydrocarbon chain to split

Question 38

What are 4 differences between alkenes and alkanes?

Answer 38

1) alkenes have a double CC bond 2) Alkenes are unsaturated 3) Alkenes are more reactive 4) Alkenes decolorise Bromine water

Question 39

Why can Alkenes form polymers by being added together?

Answer 39

They have a double CC bond which can break

Question 40

What 3 addition reactions are there of Alkenes?

Answer 40

1) with water 2) with hydrogen 3) with halogens

Question 41

What does an Alkenes reacting with water make?

Answer 41

An alcohol

Question 42

What does an Alkenes reacting with hydrogen make?

Answer 42

An alkane

Question 43

What does an Alkenes reacting with a halogen molecule make?

Answer 43

A dihalogenalkane