A2 Buffers

An acidic buffer is a:

• Solution with strong acid and weak acid

• Solution with weak acid and strong base

• Solution with weak acid and conjugate base

• Solution with strong acid and conjugate base

A buffer solution...

• Stops the pH changing

• Prevents a solution from becoming basic

• Prevents a solution from becoming acidic

• Minimises pH changes when small amounts of acid or base are added

What are two possible ways of making an acidic buffer:

• Mix a solution of a weak acid with a solution of it's conjugate salt

• Mix a solution of a strong acid with a solution of it's conjugate salt

• Mix a solution of excess weak acid with a solution of a strong base

• Mix a solution of excess weak acid with a solution of a weak base

What happens to a buffer to minimise pH changes when an alkali is added?

• The H+ ions react with the OH- ions to form water, shifting equilibrium to the right of the buffer equation

• The H+ ions react with the OH- ions to form water, shifting equilibrium to the left of the buffer equation

• The conjugate base reacts with the OH- ions, shifting equilibrium to the right of the buffer equation

• The conjugate base reacts with the OH- ions, shifting equilibrium to the left of the buffer equation

What is the optimum pH in human blood?

• 7.40

• 6.40

• 8.40

• 7

Which of these could be added to a solution of ammonia in order to form a buffer solution?

• Ethanoic acid

• Sodium Hydroxide

• Hydrochloric Acid

• Ammonium Chloride

The diagram shows a pH curve produced by adding a strong alkali to a weak acid. Which point on the curve represents a solution that can act as a buffer?

• A

• B

• C

• D

What happens when a small amount of HCl is added to a solution containing ethanoic acid and ethanoate ions.

• H⁺ + OH^- -> H₂O and equilibrium of the buffer shifts left

• CH₃COOH + H⁺ -> CH₃COOOH⁺ and equilibrium of the buffer shifts right

• CH₃COO^- + H⁺ -> CH₃COOH and equilibrium of the buffer shifts right

• CH₃COO^- + H⁺ -> CH₃COOH and equilibrium of the buffer shifts left