2.3

Question 0

Exothermic

Answer 0

Reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings

Question 1

Enthalpy

Answer 1

The heat content that is stored in a chemical system

Question 2

Endothermic

Answer 2

Refers to a reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings

Question 3

Activation energy

Answer 3

The minimum energy required to start a reaction by the breaking of bonds.

Question 4

Standard conditions

Answer 4

A pressure of 100KPa a stated temperature usually 298K and a concentration of 1 moldm-3 ( for reactions with aqueous solutions

Question 5

Standard state

Answer 5

The physical state of a substance under the standard conditions of 100KPa and 298K

Question 6

Specific heat capacity

Answer 6

The energy required to raise the temperature of 1g of a substance by 1°c

Question 7

Standard enthalpy change of combustion

Answer 7

The enthalpy change that takes place
When one mole of a substance reacts completely with oxygen
Under standard conditions all reactant and products being in their standard states.

Question 8

Standard enthalpy change of formation

Answer 8

The enthalpy change that takes place
When one mole of a compound is formed
From it’s constituent elements
In their standard states all reactants and products being in their standard states.

Question 9

Bond enthalpy

Answer 9

The enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species

Question 10

Average bond enthalpy

Answer 10

The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.

Question 11

Hess’ law

Answer 11

If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.

Question 12

Rate of reaction

Answer 12

The change in concentration of a reactant or a product in a given time.

Question 13

Standard enthalpy change of reaction

Answer 13

The enthalpy change that accompanies a reaction
In the molar quantities
Expressed in a chemical equation
Under standard conditions and all reactants and products being in their standard states.

Question 14

Heterogenous catalysis

Answer 14

Catalysis of a reaction in which the catalyst has a different physical state from the reactants

Question 15

Homogeneous catalysis

Answer 15

Catalysis of a reaction in which the catalyst and the reactants are in the same physical state

Question 16

Dynamic equilibrium

Answer 16

In a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction.

Question 17

Le Chatelier’s principle

Answer 17

When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change.