Buffer Solutions

What is the pH of a buffer solution made by mixing 100 cm³ of 0.1 mol dm⁻³ methanoic acid with 50 cm³ 0.1 mol dm⁻³ sodium methanoate? Ka (HCOOH) = 1.6 × 10 ⁻⁴

• pH 4.1

• pH 3.8

• pH 4.5

• pH 3.5

Calculate the pH of 0.0100 mol dm⁻³ benzoic acid and 0.0400 mol dm⁻³ sodium benzoate. (Ka of benzoic acid = 6.3 × 10 ⁻⁵ mol dm⁻³ )

• pH 4.8

• pH 3.5

• pH 4.5

• pH 3.8

A buffer solution is one which ...

• resists changes in pH when small quantities of an acid or an alkali are added to it

• resists changes in volume when small quantities of an acid or an alkali are added to it

• resists changes in concentration when small quantities of an acid or an alkali are added to it

Acidic buffer solutions are commonly made from a weak acid and one of its ....

• conjugate base

• conjugate acid

Which one is buffer solution of weak base & its conjugate?

• ammonia with ammonium chloride

• ammonia with ammonium hydroxide

• ethanoic acid and sodium ethanoate

• ethanoic acid and ammonium hydroxide

Why do we use double arrow in ionisation of sodium ethanoate?

• because it's reversible reaction

• because it's irreversible reaction

• because it's acid

• because it's buffer solution