Exam Definitions

Question 1

Boiling point

Answer 1

The temperature of a liquid at which its vapour pressure equals the external atmospheric pressure

Question 2

Temperature

Answer 2

The average kinetic energy of particles

Question 3

Ionisation energy

Answer 3

The energy required per mole to remove an electron from an atom in the gaseous phase

Question 4

Electron affinity

Answer 4

The amount of energy released when a neutral atom accepts an additional electron to form an anion

Question 5

Electronegativity

Answer 5

A measure of the tendency of an atom in a molecule to attract a bonding pair of electrons

Question 6

Mole

Answer 6

The amount of substance having the same number of particles as there are atoms in 12g of carbon-12

Question 7

Molar mass

Answer 7

The mass in grams of one mole of that substance

Question 8

Solution

Answer 8

Homogenous mixture of solvent and solute

Question 9

Solute

Answer 9

The substance that is dissolved in the solution

Question 10

Solvent

Answer 10

The substance in which another substance is dissolved, forming a solution

Question 11

Molar concentration

Answer 11

The amount of solute per unit volume of solution

Question 12

Intramolecular bond

Answer 12

Bond between atoms within molecules

Question 13

Covalent bond

Answer 13

Involves the sharing of at least one pair of electrons by 2 atoms

Question 14

Ionic bond

Answer 14

Involves the transfer of electrons to form cations and anions which are electrostatically attracted in an ionic crystal latice

Question 15

Metallic bonding

Answer 15

The attraction between positive kernels and a delocalised sea of electrons

Question 16

Intermolecular force

Answer 16

The force of attraction between molecules or between atoms of a noble gas

Question 17

Polar Molecule/Dipole

Answer 17

Molecule in which the electrons are unevenly distributed resulting in a δ- and δ+ end

Question 18

Heat of reaction

Answer 18

The net change of chemical potential energy of the system

Question 19

Exothermic reactions

Answer 19

Reactions which transform chemical potential energy into thermal energy

Question 20

Endothermic reactions

Answer 20

Reactions which transform thermal energy into chemical potential energy

Question 21

Activation energy

Answer 21

The minimum energy required to start a chemical reaction

Question 22

Activated complex

Answer 22

A high energy, unstable transition state between the reactants and the products

Question 23

Reaction rate

Answer 23

The change in the amount of concentration per unit time of either reactant or product

Question 24

Catalyst

Answer 24

A substance that increases the rate of the reaction but remains unchanged at the end of the reaction

Question 25

Collision Theory

Answer 25

A model that explains that a reaction will only proceed when reactant particles collide effectively

Question 26

Limiting reagent

Answer 26

The substance that is totally consumed or consumed first during a chemical reaction

Question 27

Closed system

Answer 27

A system in which mass is conserved inside the system but energy can enter or leave the system freely

Question 28

Open system

Answer 28

A system in which both energy and matter can be exchanged between the system and its surroundings

Question 29

Reversible reaction

Answer 29

A reaction in which products can be converted back into reactants.

Question 30

Dynamic equilibrium

Answer 30

A reversible reaction in which the forward and the reverse reactions are occurring simultaneously at the same rate

Question 31

Le Châtelier’s Principle

Answer 31

When an external stress is applied to a system in dynamic chemical equilibrium, the equilibrium point will change in such a way as to counteract the stress