SC20 Fuels

Question 1

How were fossil fuels made?

Answer 1

they were formed millions of years ago from the remains of dead plants and animals that were trapped in sediments under conditions of heat, pressure and absence of oxygen.

Question 2

What are hydrocarbons?

Answer 2

compounds that contain hydrogen and carbon atoms only

Question 3

What are finite resources?

Answer 3

These resources are not made any more (or are being made extremely slowly), which limits the amounts available to us

Question 3

What are non-renewable resources?

Answer 3

resources that are being used up faster than they are being formed

Question 4

What is Fractional distillation?

Answer 4

a process used to separate a mixture of liquids
that have different boiling points

Question 5

What are Fractions?

Answer 5

mixtures of hydrocarbons with similar boiling points

Question 6

How is crude oil separated into fractions?

Answer 6

1. Oil is heated to about 450°C and pumped into the bottom of a tall tower called a fractionating column or fractionating tower, where it vaporizes.
2. The column is very hot at the bottom but much cooler at the top. As the vapors rise, they cool and condense at different levels, according to their boiling temperature.
3. Heavy fractions (containing large carbon chain molecules) have a high boiling point and condense near the bottom of the column.
4. Lighter fractions (containing small carbon chain molecules) have a lower
   boiling point and condense further up the column.
5. The vapours with the lowest boiling points do not condense at all and
   leave at the top as a mixture of gases[

Question 7

Give me the order of crude oil fractions from highest boiling point to lowest.

Answer 7

Gases

petrol

kerosene

diesel oil

fuel oil

bitumen

Question 8

Name a use for gases

Answer 8

heating and cooking in homes

Question 8

Name a use for petrol

Answer 8

fuel for cars

Question 9

Name a use for kurosene

Answer 9

fuel for aircraft engines

Question 10

Name a use for diesel oil

Answer 10

fuel for diesel engines

cars trains

Question 11

Name a use for fuel oil

Answer 11

fuel for large ships

Question 12

Name a use for bitumen

Answer 12

making roads

Question 13

Why do fractions have different boiling points?

Answer 13

There are tiny forces of attraction (intermolecular forces) between all molecules.
The longer the molecule, the stronger these forces are. The stronger the forces, the more energy is needed to break them and allow the molecules to break away from the liquid and form a gas. So longer molecules have higher boiling points.

Question 14

State the trend in the properties of the fractions leaving an oil fractionating column.

Answer 14

As you go up the column:

Number of molecules goes down
Boiling point decreases
Becomes easier to ignite
Flow more easily

Question 15

What are Alkanes?

Answer 15

Alkanes are a type of hydrocarbon molecules, with C-C single bonds.

Question 16

State the features that members of a homologous series havein common.

Answer 16

1. The molecular formulae of neighbouring compounds differ by CH2
2. They have the same general formula
3. They show a gradual variation in physical properties e.g. boiling
   points
4. They have similar chemical properties

Question 17

What does the General formula show?

Answer 17

Represents the formula for a whole homologous series

Question 18

What does the Molecular formula show?

Answer 18

Shows the actual numbers of atoms of each
element in the molecules of these compounds

Question 19

What does the Empirical formula show?

Answer 19

Shows the simplest whole number ratio of
elements in the molecules

Question 20

What does the Structural formula show?

Answer 20

Shows all the atoms using subscript numbers
but not the bonds

Question 21

What does the Displayed formula show?

Answer 21

Shows all the atoms and all the bonds present
in an organic compound

Question 22

What are fuels?

Answer 22

Fuels are substances that release heat energy when
burned

Question 23

Give me 2 properties of a incomplete combustion.

Answer 23

* water is produced * energy is given out (but less than in complete combustion i.e. less efficient fuel) * carbon monoxide and carbon are produced

Question 23

When is a combustion reaction classified as complete?

Answer 23

A reaction of a hydrocarbon with a plentiful supply of air or oxygen

Question 24

Give me 2 properties of a complete combustion.

Answer 24

* only carbon dioxide and water are produced * large amount of energy is given out (i.e. makes the hydrocarbon a good fuel)

Question 25

When is a combustion reaction classified as incomplete?

Answer 25

a reaction of a hydrocarbon with a limited supply of air or oxygen

Question 26

What are the problems with soot?

Answer 26

* Blocks the pipes carrying away waste gases from an appliance * Blackens buildings * Breathing problems if it collects in the lung

Question 27

What are the problems with carbon monoxide?

Answer 27

* Colourless, odourless, toxic gas that binds irreversibly with haemoglobin preventing oxygen combining  less oxygen carried  sleepy, unconscious, even death

Question 28

What causes acid rain?

Answer 28

Oxides of nitrogen (reaction due to high temperatures in car engines) and sulfur (petrol impurity) dissolving in rainwate

Question 29

What are the effects (problems) caused by acid rain

Answer 29

Lakes and soil become more acidic Fish die Crops cannot grow Buildings and statues made of marble(carbonates) dissolve

Question 30

What is Cracking?

Answer 30

involves the breaking of large alkane molecules (obtained from crude oil) into smaller alkanes and alkenes