C5

Question 1

Reactivity

Answer 1

A measure of how reactive a substance is

Question 2

Equilibrium

Answer 2

a state of balance between opposing forces or actions

Question 3

Reactivity series

Answer 3

A list of elements arranged in order of reactivity, with the most reactive
elements at the top and the least reactive elements at the bottom

Question 4

Limiting reactant (HT 
only)

Answer 4

The reactant in a chemical reaction that is completely used up and therefore
limits the amount of products

Question 5

Collision Theory

Answer 5

The theory that explains how various factors affect rates of reaction.
Chemical reactions can occur only when reacting particles collide with each
other and with sufficient energy

Question 6

Activation energy

Answer 6

The minimum amount of energy that particles must have to react

Question 7

Chemical change

Answer 7

A change in which one or more new substances are produced

Question 8

Oxidisation

Answer 8

The loss of electrons from a substance or the gain of oxygen by a substance

Question 9

Reduction

Answer 9

The gain of electrons by a substance or the loss of oxygen from a substance

Question 10

Redox reaction

Answer 10

A reaction in which one substance is reduced and another is oxidised

Question 11

Dilute

Answer 11

A solution with a small number of molecules of a substance in a given volume

Question 12

Ionic equation

Answer 12

shows only the atoms and ions that changes in a reaction.

Question 13

Half equation

Answer 13

A symbol equation that shows how individual atoms or ions gain or lose
electrons

Question 14

Ores

Answer 14

Rocks from which it is economical to extract the metals that they contain

Question 15

Metal ore

Answer 15

Naturally occurring rocks that contain metals or metal compounds in
sufficient amounts to make it worthwhile extracting them

Question 16

Mining

Answer 16

The process of obtaining minerals from the Earth

Question 17

Metal Oxide

Answer 17

A chemical compound formed when a metal reacts with oxygen. It produces a
salt and water when it reacts with an acid

Question 18

Metal carbonate

Answer 18

A type of base characterised by the presence of a carbonate ion (CO3
2-). It
produces a salt, water and carbon dioxide when it reacts with an acid

Question 19

Metal hydroxide

Answer 19

A type of base characterised by the presence of a hydroxide ion (OH-
). It
produces a salt and water when it reacts with an acid

Question 20

Carbonate ion

Answer 20

An ion with the formula CO3
2-. Compounds containing this ion are called
carbonates

Question 21

Limestone

Answer 21

A sedimentary rock composed mainly of calcium carbonate

Question 22

Limewater

Answer 22

An aqueous solution of calcium hydroxide. It turns milky (cloudy) in the
presence of carbon dioxide

Question 23

Neutralisation reaction

Answer 23

A reaction between an acid and a base or an acid and an alkali, forming a salt 
and water (Acid + Base - a salt + water)

Question 24

Neutral

Answer 24

A substance with a pH of 7

Question 25

Alkali

Answer 25

Substances that produce more hydroxide ions than hydrogen ions when dissolved in water

Question 26

Alkaline

Answer 26

Alkalis form alkaline solutions in water. Alkalis produce hydroxide ions, OHin aqueous solution

Question 27

Alkalinity

Answer 27

The capacity of a substance to neutralise an acid

Question 28

Bases

Answer 28

A substance that reacts with an acid to neutralise it, e.g. metal oxides, metal hydroxides and metal carbonates

Question 29

Hydroxide ion

Answer 29

A negatively charged ion with the chemical formula OH- , found in alkaline solutions

Question 30

Acid

Answer 30

A substance that produces hydrogen ions (H+ ) in aqueous solutions and has a pH of less than 7

Question 31

Acidity

Answer 31

The concentration of hydrogen ions (H+ | ) in a substance

Question 32

Hydrogen ion

Answer 32

A positively charged ion with the chemical formula H+ , found in acidic solutions

Question 33

Salts

Answer 33

A compound formed by the neutralisation of an acid by a base. Formed when the hydrogen in an acid is wholly or partially replaced by metal or ammonium ions

Question 34

Formation of salts

Answer 34

Made by reacting suitable metal and an acid, The metal must be above hydrogen in the reactivity series. The reaction produces hydrogen gas and a salt

Question 35

Weak acids

Answer 35

Acids that do not ionise completely in aqueous solutions

Question 36

Strong acids

Answer 36

These acids completely ionise in aqueous solution

Question 37

pH

Answer 37

A measure of the acidity or alkalinity of a substance on a scale of 0 to 14. Values less than 7 indicates acidic. Values above 7 indicate alkaline. Value of 7 indicates a neutral solution

Question 38

ph scale

Answer 38

A scale from 0 to 14 that is used to measure the acidity or alkalinity of a substance. As pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10

Question 39

Universal indicator

Answer 39

A mixture of dyes that changes color gradually over a range of pH, used to test for acids and alkalis

Question 40

Litmus paper

Answer 40

Indicator paper used to test pH. Red paper turns blue in alkaline solutions and blue paper turns red in acidic solutions. It is bleached white in the presence of chlorine