Fuels and Heats of Reactions

Question 1

Define organic chemistry.

Answer 1

Organic chemistry is the study of the compounds of carbon

Question 2

What is a hydrocarbon?

Answer 2

A hydrocarbon is a compound that contains carbon and hydrogen only

Question 3

Define fossil fuels.

Answer 3

Fossil fuels are fuels that were formed from the remains of plants and animals that lived millions of years ago

Question 4

What is a saturated compound?

Answer 4

A saturated compound is one in which there are only single bonds between the atoms in the molecule

Question 5

Define a homologous series.

5

Answer 5

A series of compounds of similar chemical properties

Showing gradations 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 6

What are structural isomers?

Answer 6

Compounds with the same molecular formula but different structural formulas

Question 7

What is an unsaturated compound?

Answer 7

An unsaturated compound is one that contains one or more double or triple bonds between the atoms in a molecule

Question 8

What is an aliphatic compound?

Answer 8

An organic compound that consists of open chains of carbon atoms and closed chain compounds (rings) that resemble them in chemical properties

Question 9

Define an aromatic compounds.

Answer 9

Aromatic compounds are compounds that contain a benzene ring structure in their molecule

Question 10

Define auto-ignition.

Answer 10

Auto-ignition is premature ignition (explosion) of the petrol-air mixture before normal ignition of the mixture by a spark takes place

Question 11

What is octane number?

Answer 11

The octane number of a fuel is a measure of the tendency of the fuel to resist knocking

Question 12

Define catalytic cracking.

Answer 12

Catalytic cracking is the breaking down of long-chain hydrocarbon molecules by the action of heat and catalysts into short-chain molecules for which there is greater demand

Question 13

Define heat of reaction.

Answer 13

Heat of reaction is the heat change when the numbers of moles of reactants indicated in the balanced equation for the reaction react completely

Question 14

Define heat of combustion.

Answer 14

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

Question 15

What is the kilogram calorific value of a fuel?

Answer 15

The kilogram calorific value of a fuel is the heat energy produced when 1kg of the fuel is completely burned in oxygen

Question 16

Define bond energy.

Answer 16

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

Question 17

Define heat of neutralisation.

Answer 17

Heat of neutralisation is the heat change when one mole of H+ ions from an acid reacts with one mole of OH- ions from a base

Question 18

Define heat of formation.

Answer 18

The heat of formation of a compound is 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 19

Define Hess’s Law

Answer 19

Hess’s Law states that 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 20

Define The Law Of Conservation of Energy

Answer 20

The Law of Conservation of Energy states that energy cannot be created or destroyed but can only be converted from one form of energy into another