pH Value (2)

Uses of the concentration of hydroxide ion, OH–

Is used to calculate the value of pOH of an alkali

Formula to calculate the value of pOH of an alkali

pOH = –log [OH–]

Definition of [OH–] in formula (pOH = –log [OH–])

[OH–] represents the concentration of hydroxide ions in mol dm–3 of the alkali solution

The sum of pH value and pOH value

Is 14

The relationship between concentration of hydrogen ions, H+ with the pH value (1)

When the concentration of acid increases, more acid molecules ionise to produce hydrogen ions, H+

The relationship between concentration of hydrogen ions, H+ with the pH value (2)

The higher the concentration of hydrogen ions, H+, the lower the pH value

The relationship between concentration of hydrogen ions, H+ with the pH value (3)

Acidity increases when the pH value of the acid solution decreases

The relationship between concentration of hydroxide ions, OH– with the pH value (1)

The higher the concentration of hydroxide ions, OH–, the higher the pH value

The relationship between concentration of hydroxide ions, OH– with the pH value (2)

Alkalinity increases when the pH value of the alkaline solution increases

Way to determine the pH value of various substances (1)

By using universal indicator