C9- Crude Oil And Fuels

Question 1

What is Crude oil?

Answer 1

A finite resource found in rocks. It was formed over millions of years from the remains of tiny, ancient sea animals and plants ( mainly plankton).

Question 2

What is crude oil’s appearance?

Answer 2

It is a dark, smelly liquid. It is a mixture of different carbon compounds.

Question 3

What is a mixture?

Answer 3

A mixture contains two or more elements or compounds that are not chemically combined together.

Question 4

What needs to be done to crude oil in order to make it useful?

Answer 4

It must be separated into different substances with similar boiling points. These are known as fractions.

Question 5

Name the first four Alkanes

Answer 5

CH4
C2H6
C3H8
C4H10

Question 6

What is the formula for propane?

Answer 6

C3H8

Question 7

What is the formula for Ethane?

Answer 7

C2H6

Question 8

What is the general formula for Alkanes?

Answer 8

Cn H(2n+2)

Question 9

Why can Alkanes be described as Saturated Hydrocarbons?

Answer 9

All the Carbon-Carbon bonds are single covalent bonds. This means that they contain as many hydrogen atoms as possible in each molecule.

Question 10

Which chain-length hydrocarbons tend to be most useful?

Answer 10

The short-chain molecules

Question 11

Key features of Short Chain Hydrocarbons

Answer 11

Lower boiling point
Higher volatility
Low viscocity (very runny)
Higher flammability

Question 12

Key features of long chain hyrocarbons

Answer 12

Higher boling point
Lower volatility
High viscocity
Lower flammability

Question 13

What is flammability?

Answer 13

How easily sonething burns

Question 14

What is viscocity?

Answer 14

How easily something flows

Question 15

What is volatility?

Answer 15

The tendency for something to turn into a gas

Question 16

What is boiling point?

Answer 16

The temperature at which the liquid boils or the gas condenses

Question 17

What is fractional distillation?

Answer 17

Where crudeoil is separated into hydrocarbons with similar boiling points called fractions

Question 18

What do hydrocarbons have to have to be in the same fraction?

Answer 18

Molecules with similar numbers of carbon atoms

Question 19

Fractional distillation Explained

Answer 19

Crude oil is heated and fed in near the bottom of a tall tower (called a fractionating column) as hot vapour. The column is kept very hot at the bottom and much cooler at the top, so the temperature decreases going up the column. The gases move up the column and the hydrocarbons condense when they reach the temperature of their boiling points. The different fractions are collected as liquids at different levels. The fractions are collected from the column in a continuous process.

Question 20

What is the name of the apparatus where fractional distillation takes place?

Answer 20

Fractionating column

Question 21

What is at the top of the fractionating column (lowest temp of 50 degrees)

Answer 21

Refinery/petroleum gas

Question 22

What is at the bottom of the fractionating column (highest temp of 350 degrees)

Answer 22

Residue

Question 23

Fractionating column in order (starting from the bottom and highest temp)

Answer 23

Residue
Diesel oil/ gas oil (diesel engines and as boiler fuel)
Kerosene ( aircraft fuel )
Gasoline/petrol ( fuel in car engines)
Refinery / petroleum gas ( used as fuel)

Question 24

What are the products of the complete combustion of a hydrocarbon?

Answer 24

Carbon dioxide and water

Question 25

What colour does white anhydrous copper sulfate turn on contact with water ( testing for products of complete combustion)?

Answer 25

Blue

Question 26

What is the toxic product formed in incomplete combustion?

Answer 26

Carbon monoxide- binds to red blood cells instead of oxygen

Question 27

Why crack hyrocarbons?

Answer 27

Because some heavier fractions are not in high demand and smaller ones are more useful and are in higher demand.

Question 28

What is the name of the process where larger hydrocarbon molecules are broken down into smaller more useful ones?

Answer 28

Cracking

Question 29

Which two ways are used for cracking hydrocarbons?

Answer 29

The process takes place in steel vessels called crackers. The heavy fractions are heated to vaporise the hydrocarbons. The vapour is then either:
. Passed over a hot catalyst, or
. Mixed with steam and heated to a very high temperature

Question 30

What type of reaction takes place during cracking?

Answer 30

Thermal decomposition reactions take place as the large molecules split apart to form smaller ones

Question 31

What suffix/ending do unsaturated hydrocarbons have?

Answer 31

-ene

Question 32

What is the difference between alkanes and alkenes ?

Answer 32

Alkene molecules have two fewer hydrogen atoms than alkanes with the same number of carbon atoms.

Question 33

Test for an unsaturated hydrocarbon

Answer 33

It turns orange bromine water colourless

Question 34

What is Combustion?

Answer 34

Fuels react with oxygen to release energy

Question 35

Conditions for complete combustion

Answer 35

Plentiful supply of air (oxygen)

Question 36

Conditions for incomplete combustion

Answer 36

Supply of air is limited (lack of oxygen)

Question 37

Unwanted products of incomplete combustion

Answer 37

Carbon monoxide, unburnt hydrocarbon and soot

Question 38

Product of Combustion of Sulfur

Answer 38

Sulfur dioxide (can cause acid rain)

Question 39

Products of reaction of Nitrogen and oxygen (at high temp and often in engines)

Answer 39

Nitrogen oxides (cause acid rain)

Question 40

How to reduce problem of acid rain

Answer 40

Sulfur dioxide- Remove by flue gas desulfurisation
Nitrogen oxides- Catalytic converters in cars