Organic Chemistry

Question 1

What is a hydrocarbon ?

Answer 1

A hydrocarbon is any compound that is formed by only carbon and hydrogen atoms

Question 2

What is an Alkane ?

Answer 2

The most simple type of hydrocarbon you can get .

Solid to be saturated - means that these atoms are helps together by single bonds

Question 3

What do the saturated molecules contain ?

Answer 3

They contain : a carbon carbon covalent bond (c-c)

Question 4

Alkanes are part of what series ?

Answer 4

Homologous series - a group of organic compounds that react in a similar way .

Question 5

Alkanes are saturated compounds

Each carbon atom forms what type of bond ?

Answer 5

4 single covalent bonds

Question 6

What are the first 4 alkanes ?

Answer 6

Methane - CH4
Ethane - C3H8
Propane - C2H6
Butane -

Question 7

What happens as the length of the carbon chain changes ?

Answer 7

The properties of the hydrocarbon changes

Question 8

The shorter the carbon chain …

Answer 8

• Lower boiling point
• Higher volatility
• Low viscosity (very runny )
• Highly flammable

Question 9

The longer the carbon chain ….

Answer 9

• Higher boiling point
• Lower volatility
• Higher viscosity ( thick )
• Lower flammability

Question 10

Hydrocarbons with a lower carbon chain are …

Answer 10

More volatile - lower boiling points

Question 11

A shorter carbon is also more …

Answer 11

Flammable the hydrocarbon is

Question 12

The properties of the hydrocarbons affect how they can be used for fuels …. For example :

Answer 12

Shorter chain hydrocarbons with lower boiling points are used as bottle gases - stored under pressure as liquids in bottles

Question 14

What is viscosity ?

Answer 14

How easily it flows

Question 15

What is volatility ?

Answer 15

How likely to turn into a gas it is

Question 16

What is fractional distillation ?

Answer 16

Separation of a liquid mixture into fractions differing in boiling points , typically using a fraction sing column

Question 17

Explained steps involved in the fractional distillation of crude oil

Answer 17

Crude oil enters the fractions get column as a vapour

As you go up the temperature decreases

Gases condense at their boiling point

Different fractions collected as liquids at the different levels

Fractions with lower boiling points collect at the top

Fractions with higher boiling points collect at the bottom

Question 18

When burning hydrocarbons we burn them in plenty of air and the energy transfers to where?

Answer 18

The surroundings

Question 19

The most common hydro carbon burnt is propane

What is the word equation

Answer 19

Propane + Oxygen = carbon dioxide + water

Question 20

Why do we crack hydrocarbons ?

Answer 20

To make much smaller and much more useful hydrocarbons - these are in high demand
Longer chain are not as useful

Question 21

How do we crack hydrocarbons ?

Answer 21

1 . Heated vapour is then passed over a hot catalyst

2 . Mixed with steam and heated to a high temp ( thermal decomposition )

Question 22

What is an Alkene ?

Answer 22

An Alkene tells us they are unsaturated. They have at least on double carbon bond ( c=c )

Question 23

What is incomplete combustion ?

Answer 23

Incomplete combustion will occur when there is not enough oxygen to allow the fuel to react completely to produced carbon dioxide and water

Question 24

What is the difference between a saturated and an unsaturated hydrocarbon ?

Answer 24

Alkane - ( c-c ) single carbon bond ( saturated )

Alkene - (c=c) double carbon bond ( unsaturated )

Question 25

What is the test to find out if a hydrocarbon is saturated or unsaturated ?

Answer 25

A positive test for an UNSATURATED hydrocarbon is that it turn orange bromine water colourless where as if it was SATURATED it would remain orange
(Alkanes don’t react with water ) - therefore we can see what the hydrocarbon is