Alkanes and Crude Oil (TOPIC 3)

Question 1

What is a Hydrocarbon?

Answer 1

A compound containing Hydrogen and Compound atoms only.

Question 2

What is the Empirical Formula?

Answer 2

The simplest whole number ratio of atoms of each element in a compound.

Question 3

What is the Homologous Series?

Answer 3

A group of organic compounds with the same general formula and whose members differ from the next by a CH2 group.

Members of the same Homologous series have a trend in physical and similar chemical properties.

Same functional group
Members differ from the next by CH2 group
React similarly

Question 4

What is Isomerism?

Answer 4

Isomers are compounds that have the same molecular formula but different displayed formulae

Question 5

What is the general formula for Alkanes?

Answer 5

CnH2n+2

Question 6

Why are alkanes classed as saturated hydrocarbons

Answer 6

because their carbons are single-bonded.

Question 7

What is fuel?

Answer 7

A substance when burnt releases heat energy.

Question 8

What are the products of complete combustion?

Answer 8

Hydrocarbon + oxygen → carbon dioxide + water

Question 9

What are the products of incomplete combustion?

Answer 9

Hydrocarbon + oxygen → carbon monoxide + carbon + water

Question 10

Why is Carbon Monoxide dangerous?

Answer 10

It combines with red blood cells and limits the capacity of oxygen being transferred around the body.

Question 11

How does Nitrogen OXide form and what are the problems of this?

Answer 11

Heat from the engine cause Nitrogen + oxygen in the air to burn this can cause acid rain

Question 12

How does Sulfur dioxide form and what are the problems of this?

Answer 12

Caused by the burning of fuels containing sulfur

Causes acid rain

Question 13

What are the issues of Acid Rain?

Answer 13

Damages buildings
Acid rains cause lakes to become acidic and as a result plants and aquatic life die

Question 14

Describe the separation technique - Simple Distillation

Answer 14

Used for separating out solutions.

Heat the solution and the part that has the lowest boiling point will evaporate. The vapor is cooled and condensed in the condenser. The rest of the solution is left behind in the flask.

Question 15

Describe the separation technique - Fractional Distillation

Answer 15

Used for separating mixtures eg. crude oil

Heat the mixture, the part with the lowest boiling point will evaporate first and will rise up the fractionating column. When you have collected this fraction you increase the temperature and the part with the next lowest boiling point will rise etc…

Question 16

What is Crude Oil?

Answer 16

A complex mixture of Hydrocarbons

Question 17

How is Crude Oil seperated into its different fractions?

Answer 17

Using a fractionating column that is cooler at the top than at the bottom so when it is heated the vapor rises and when it reaches a part cooler than its boiling point it condenses into their different fractions.

Question 18

What are the names and uses of the differnet crude oil fractions.

Answer 18

Starting at the bottom:

Bitumen - used to surface roads
Fuel Oil - Uses as fuel on larger ships and in some power stations
Diesel - Used as a fuel in some cars and larger veichles
Kerosene - fuel in aircrafts
Gasoline - Used as a fuel in cars
Refinery Gases - Used in domestic cooking and heating

Question 19

What is the trend in colour boiling point and viscosity in the main fractions?

Answer 19

Boiling point decreases as you go up the fraction

viscosity decreases as you go up the fraction

Colour is darkest at the bottom and lightest at the top