Fuels and Heats of Reactions

Question 1

What are hydrocarbons

Answer 1

Compound that contains carbon and hydrogen only.

Question 2

What are fossil fuels

Answer 2

Fuels that were formed from the remains of plants and animals that lived millions of years ago.

Question 3

What is a saturated compound?

Answer 3

There are only single bond between the atoms in the molecule.

Question 4

What are alkanes

Answer 4

Saturated compounds

Question 5

What are isomers

Answer 5

Compounds with the same molecular formula but different structural formulas.

Question 6

What are alkenes

Answer 6

Unsaturated compounds

Question 7

What is a unsaturated compound

Answer 7

Contains one or more double or triple bonds between the atoms in the molecule.

Question 8

What is a functional group

Answer 8

Atom or a group of atoms which is responsible for the characteristic properties of an organic compound or series of organic compounds,.

Question 9

What is a homologous series

Answer 9

A series of compounds of similar chemical properties, showing gradation in physical properties, having a general formula for its members, each member having a similar method of preparation, each member differing from the previous member by a CH2 unit.

Question 10

What is an aliphatic compound

Answer 10

Organic compound that consists of open chains or carbon atoms and close chain compounds(rings) that resemble them in chemical properties.

Question 11

What is an aromatic compound?

Answer 11

Compounds that contain a benzene ring structure in their molecules.

Question 12

Fractional distillation of crude oil

Answer 12

RPN KDL FB
Refinery gas - 25
Petrol - 50
Naphtha - 100
Kerosene - 200
Diesel - 300
Lubricating Oil - 400
Fuel oil - 450
Bitumen - 500

Question 13

What is a mercaptan

Answer 13

Sulfur compound added to gas(LPG) to give it a smell

Question 14

What is pre-ignition?

Answer 14

Early explosion that can occur if the mixture isn’t correct.

Question 15

What is auto-ignition

Answer 15

Premature ignition (explosion) of the petrol-air mixture before normal ignition of the mixture by a spark takes place.

Question 16

What is the octane number

Answer 16

Measure of the tendency of a fuel to resist knocking

Question 17

What are the factors for a high octane number

Answer 17

• Short chain
• Lots of branching
• Cyclic Structure

Question 18

What is Isomerisation

Answer 18

Changing straight chained compounds into their isomers. Compounds are now more branched

Question 19

What is Catalytic cracking

Answer 19

The breaking down of long chain hydrocarbon molecules by the action of heat and catalysts into short chain molecules. An alkene is always produced.

Question 20

What is dehydrocyclisation

Answer 20

Use of catalysts to for ring compounds from straight chained compounds.

Question 21

What is bond energy

Answer 21

The average energy required to break up one mole of a substance of a particular covalent bond and to separate the neutral atoms completely from each other

Question 22

What is the Heat of Neutralisation

Answer 22

Heat change when one mole of H+ ions from an acid reacts with one mole of OH minus ions from a base

Question 23

What is specific heat capacity

Answer 23

The amount of energy required to raise the temperature of 1kg of a substance by 1K

Question 24

What are exothermic reactions?

Answer 24

Reactions that release heat (any combustions reaction)

Question 25

What are endothermic reactions?

Answer 25

Reactions that take in heat (salt in water)

Question 26

What is the heat of reaction

Answer 26

The heat change when the number of moles of reactants indicated in the balanced equation react completely.

Question 27

What is the heat of combustion

Answer 27

The heat change when one mole of a substance is completely burned in excess oxygen

Question 28

What is the heat of formation?

Answer 28

The heat change that takes place when one mole of a compound in its standard state is formed from its elements in their standard states.

Question 29

What is Hess’s Law

Answer 29

If a chemical reaction takes place in a number of stages, the sum of the heat changes in the separate stages is equal to the heat change if the reaction is carried out in one stage.

Question 30

What is the kilogram calorific value?

Answer 30

Heat energy produced when 1kg of the fuel is completely burned in oxygen.