Buffer solutionsAQA A-Level Chemistry: Mind map

Exam questions on Buffer solutions

1. A technician prepares a buffer solution by dissolving solid sodium ethanoate in a solution of ethanoic acid.
   Explain how this buffer solution resists a change in pH when a small amount of sodium hydroxide solution is added.2 marks
2. A laboratory needs a buffer to hold a solution at an alkaline pH. The technician mixes aqueous ammonia with a solution of ammonium chloride.
   Explain how this buffer resists a change in pH when a small amount of sodium hydroxide solution is added.2 marks
3. A student prepares a buffer by mixing 50.0 cm³ of 0.200 mol dm⁻³ methanoic acid, HCOOH, with 25.0 cm³ of 0.100 mol dm⁻³ sodium methanoate, HCOONa. For methanoic acid, $K_a = 1.78 \times 10^{-4}$ mol dm⁻³ at 298 K.
   Calculate the pH of the buffer solution. Give your answer to 3 significant figures.3 marks