All IEB Definitions for Chemistry

Question 1

Molar mass

Answer 1

the mass in grams of one mole of that substance.

Question 2

Solution

Answer 2

a homogenous mixture of solute and solvent.

Question 3

Solute

Answer 3

the substance that dissolved in the solution.

Question 4

Solvent

Answer 4

the substance in which another substance is dissolved, forming a solution.

Question 5

Concentration

Answer 5

the amount of solute per unit volume of solution.

Question 6

Yield

Answer 6

a measure of the extent of a reaction, generally measured by comparing the amount of product against the amount of product that is possible.

Question 7

Intramolecular bond

Answer 7

a bond which occurs between atoms within molecules.

Question 8

Intermolecular force

Answer 8

a force of attraction between molecules, ions, or atoms of noble gases.

Question 9

Covalent bond

Answer 9

a sharing of at least one pair of electrons by two non-metal atoms.

Question 10

Non-polar covalent (pure covalent)

Answer 10

an equal sharing of electrons.

Question 11

Polar covalent

Answer 11

an unequal sharing of electrons leading to a dipole forming.

Question 12

Ionic bond

Answer 12

a transfer of electrons and subsequent electrostatic attraction.

Question 13

Metallic bonding

Answer 13

bonding between a positive kernel and a sea of delocalised electrons.

Question 14

Electronegativity

Answer 14

a measure of the tendency of an atom to attract a bonding pair of electrons.

Question 15

Organic molecules

Answer 15

molecules containing carbon atoms.

Question 16

Hydrocarbon

Answer 16

a compound containing only carbon and hydrogen atoms.

Question 17

Homologous series

Answer 17

a series of similar compounds which have the same functional group and have the same general formula, in which each member differs from the previous one by a single CH2 unit.

Question 18

Saturated compound

Answer 18

a compound in which all of the bonds between carbon atoms are single bonds.

Question 19

Unsaturated compound

Answer 19

a compound in which there is at least one double and/or triple bond between carbon atoms.

Question 20

Functional group

Answer 20

an atom or a group of atoms that form the centre of chemical activity in the molecule.

Question 21

Structural isomers

Answer 21

compounds having the same molecular formula but different structural formulae.

Question 22

Heat of reaction (ΔH)

Answer 22

the net change of chemical potential energy of the system.

Question 23

Exothermic reactions

Answer 23

reactions which transform chemical potential energy into thermal energy.

Question 24

Endothermic reactions

Answer 24

reactions which transform thermal energy into chemical potential energy.

Question 25

Activation energy

Answer 25

the minimum energy required to start a chemical reaction or the energy required to form the activated complex.

Question 26

Activated complex

Answer 26

a high energy, unstable, temporary transition state between the reactants and the products.

Question 27

Reaction rate

Answer 27

the change in concentration per unit time of either a reactant or product.

Question 28

Catalyst

Answer 28

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

Question 29

Closed system (in chemistry)

Answer 29

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

Question 30

Open system (in chemistry)

Answer 30

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

Question 31

Le Châtelier's principle

Answer 31

when an external stress (change in pressure, temperature or concentration) is applied to a system in dynamic chemical equilibrium, the equilibrium point will change in such a way as to counteract the stress.

Question 32

Lowry-Brønsted theory

Answer 32

an acid is defined as a proton donor. A base is defined as a proton acceptor.

Question 33

Ionisation

Answer 33

the reaction of a molecular substance with water to produce ions.

Question 34

Strong acid

Answer 34

an acid that ionises completely in an aqueous solution.

Question 35

Weak acid

Answer 35

an acid that only ionises partially in an aqueous solution.

Question 36

Dissociation

Answer 36

the splitting of an ionic compound into its ions.

Question 37

Strong base

Answer 37

a base that dissociates completely in an aqueous solution.

Question 38

Weak base

Answer 38

a base that only dissociates/ionises partially in an aqueous solution.

Question 39

Amphoteric (amphiprotic) substance

Answer 39

a substance that can act as either an acid or a base.

Question 40

Neutralisation (equivalence point)

Answer 40

the point where an acid and base have reacted so neither is in excess.

Question 41

Salt

Answer 41

a substance in which the hydrogen of an acid has been replaced by cation.

Question 42

Hydrolysis of a salt

Answer 42

a reaction of an ion (from a salt) with water.

Question 43

Standard solution

Answer 43

a solution of known concentration.

Question 44

Redox reaction

Answer 44

a reaction involving the transfer of electrons.

Question 45

Oxidation

Answer 45

the loss of electrons.

Question 46

Reduction

Answer 46

the gain of electrons.

Question 47

Oxidising agent

Answer 47

a substance that accepts electrons.

Question 48

Reducing agent

Answer 48

a substance that donates electrons.

Question 49

Anode

Answer 49

the electrode where oxidation takes place.

Question 50

Cathode

Answer 50

the electrode where reduction takes place.

Question 51

Electrolyte

Answer 51

a substance that can conduct electricity by forming free ions when molten or dissolved in solution.