Alkalinity - used to describe the strength of an alkali 

Concentrated solution - a solution in which the concentration of solute is high

Data-logger - a device used to record and store the data

Dilute solution - a solution in which the concentration of solute is low

Molarity - the number of moles of solute dissolved in 1 dm³ of the solution; the units are mol dm^–3 or M

pH meter - a piece of apparatus that can be used to determine the pH of a solution accurately

pH scale - the common method of indicating acidity by using a logarithm scale on the values of concentration of hydrogen ions

pH sensor - a device used to determine the pH of a solution accurately; usually used with a data-logger

Strong acid - an acid that almost completely dissociates in water

Strong alkali - an alkali that almost completely dissociates to give hydroxide ions (OH^–(aq)) in water

Weak acid - an acid that only partially dissociates in water

Weak alkali - an alkali that only partially dissociates to give hydroxide ions (OH^–(aq)) in water