Matric Chem Definitions

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 is 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

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

covalent bond

Answer 8

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

Question 9

Non-polar covalent

Answer 9

an equal sharing of electrons

Question 10

polar covalent

Answer 10

unequal sharing of electrons leading to a dipole forming (as a result of electronegativity difference)

Question 11

electronegativity

Answer 11

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

Question 12

ionic bond

Answer 12

a transfer of electrons and subsequent electrostatic attraction

Question 13

metallic bond

Answer 13

being between a positive kernel and a sea of delocalised electrons

Question 14

intermolecular forces

Answer 14

weak force of attraction between molecules, ions, or atoms of noble gases

Question 15

redox reaction

Answer 15

a reaction involving the transfer of electrons

Question 16

oxidation

Answer 16

the loss of electrons

Question 17

reduction

Answer 17

the gain of electrons

Question 18

oxidising agent

Answer 18

a substance that accepts electrons

Question 19

reducing reagent

Answer 19

a substance that donates electrons

Question 20

heat of reaction

Answer 20

the net change of chemical potential energy of the system

Question 21

exothermic reaction

Answer 21

reactions which transform chemical potential energy into thermal energy

Question 22

endothermic reaction

Answer 22

reactions which transform thermal energy into chemical potential energy

Question 23

activation energy

Answer 23

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

Question 24

activated complex

Answer 24

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

Question 25

reaction rate

Answer 25

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

Question 26

Catalyst

Answer 26

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

Question 27

standard solution

Answer 27

a solution of known concentration

Question 28

electrolyte

Answer 28

Define an electrolyte as a substance that can conduct electricity by forming free ions when
molten or dissolved in solution

Question 29

hydrocarbon

Answer 29

a hydrocarbon as a compound containing only carbon and hydrogen atoms

Question 30

saturated compound

Answer 30

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

Question 31

an unsaturated compound

Answer 31

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

Question 32

functional group

Answer 32

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

Question 33

Homologous series

Answer 33

an homologous series as 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 34

structural isomers

Answer 34

structural isomers as compounds having the same molecular formula but different structural
formulae

Question 35

dissociation

Answer 35

Define dissociation as the splitting of an ionic compound into its ions

Question 36

A closed system

Answer 36

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

Question 37

Open system

Answer 37

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

Question 38

Le chatelier’s

Answer 38

‘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 39

Lowry-Brønsted Acid

Answer 39

Proton Donor

Question 40

Lowry-Brønsted Base

Answer 40

Proton Acceptor

Question 41

Ionisation

Answer 41

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

Question 42

Strong acid

Answer 42

an acid that ionises completely in an
aqueous solution

Question 43

weak Acid

Answer 43

as an acid that only ionises partially in an
aqueous solution

Question 44

Strong Base

Answer 44

base that dissociates completely in an
aqueous solution

Question 45

Weak Base

Answer 45

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

Question 46

amphoteric (or amphiprotic) substance

Answer 46

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

Question 47

Kw for water at 25 °C

Answer 47

Kw = [H3O+][OH-]

Question 48

hydrolysis of a Salt

Answer 48

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

Question 49

neutralisation (or the equivalence point)

Answer 49

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