Quelpr
3 marksAcid/Base Equilibria

CAPE Chemistry Unit 1 · 2006 · Paper 2 · Question 4(b)(i)c)

The terms Ka, pKa and pH can be used to indicate the relative strength of weak acids. The general equation for the equilibrium of a weak acid is given below: HA(aq) <=> H+(aq) + A-(aq)

Write an expression for EACH of the following terms: pH

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 4(a)(i)Describe the features of a chemical system in a state of dynamic equilibrium.[4 marks]
  2. 4(a)(ii)Define the term 'equilibrium constant'.[1 mark]
  3. 4(a)(iii)Describe and explain, with reference to changes in colour, the observations made when hydrogen gas is reacted with iodine gas at constant temperature until…[5 marks]
  4. 4(a)(iv)a)Use the information in Table 3 and the equation in (a) (iii) above to calculate the number of moles of hydrogen reacting.[3 marks]
  5. 4(a)(iv)b)Complete the table by inserting the equilibrium concentrations of I2 and HI.[3 marks]
  6. 4(a)(v)Write an equation for Kp for the reaction in (iii) above.[2 marks]
  7. 4(b)(i)a)Write an expression for EACH of the following terms: Ka[3 marks]
  8. 4(b)(i)b)Write an expression for EACH of the following terms: pKa[3 marks]
  9. 4(b)(ii)Given that Ka for acid HP is 3.0 x 10-5 mol dm-³, predict the relative size of Ka for a stronger acid HQ. Explain your reasoning.[2 marks]

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