Quelpr
4 marksAcid/Base Equilibria

CAPE Chemistry Unit 1 · 2007 · Paper 2 · Question 2(b)(v)

A chemist extracts the methanoic acid from 40 ants and adds water to make 25.00 cm³ of a Solution Y. He then titrates this solution with a 0.050 mol dm⁻³ standard solution of sodium hydroxide, NaOH(aq), a strong alkali, to determine the concentration of HCOOH in Solution Y.

Sketch a graph to illustrate the changes in pH that take place during the titration.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 2(a)(i)Explain what is meant by the term 'weak acid'.[1 mark]
  2. 2(a)(ii)Write an expression for the dissociation constant, Kₐ, of methanoic acid.[1 mark]
  3. 2(b)(i)Using Bronsted-Lowry theory, explain what is meant by a strong base.[2 marks]
  4. 2(b)(ii)Calculate the pH of the standard NaOH solution.[2 marks]
  5. 2(b)(iii)The concentration of methanoic acid in Solution Y is found to be 6.0 x 10⁻³ mol dm⁻³. Calculate the pH of Solution Y.[2 marks]
  6. 2(b)(iv)Suggest a suitable indicator for the titration between methanoic acid and sodium hydroxide.[1 mark]
  7. 2(c)Ant stings can be treated with baking soda, NaHCO₃. Suggest, with the aid of an equation, how baking soda helps to relieve the effect of the sting.[2 marks]

More practice: the rest of this paper · more Acid/Base Equilibria questions · all CAPE Chemistry Unit 1 past papers