Question 1

Which two solutions, both of concentration 0.10 mol dm-3, have been used to produce this titration curve?

  A  

HCl(aq) and KOH(aq)

  B  

HCOOH(aq) and KOH(aq)

  C  

HCl(aq) and NH3(aq)

  D  

HCOOH(aq) and NH3(aq)

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Question 2

When equimolar amounts of the solutions below are mixed, which forms a buffer solution with a pH less than 7?

  A  

hydrochloric acid and sodium chloride

  B  

ethanoic acid and sodium ethanoate

  C  

sodium hydroxide and sodium chloride

  D  

ammonia and ammonium chloride

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Question 3

The indicator methyl orange is a weak acid and may be represented by the formula HA(aq). The equation for its dissociation is shown below.

HA(aq)        ⇌.       A-        +        H+(aq)

                                                       Colour:        Red                  Yellow

Under certain conditions, at equilibrium, a solution of HA has a yellow colour.

On addition of a small volume of dilute sodium hydroxide, the colour of this solution would

  A  

change from yellow to red

  B  

change from yellow to orange

  C  

change from yellow to orange and then to red

  D  

not change

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Question 4

A buffer solution is prepared by mixing 200 cm3 of 2.00 mol dm-3 propanoic acid, CH3CH2COOH, with 600 cm3 of 1.00 mol dm-3 sodium propanoate, CH3CH2COONa.

Ka for CH3CH2COOH = 1.32 × 10-5 mol dm-3

What is the pH of the buffer solution?

  A  

4.58

  B  

4.70

  C  

5.06

  D  

5.18

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Question 5

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  

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Question 6

A 0.10 mol dm-3 aqueous solution of an acid is added slowly to 25 cm3 of a 0.10 mol dm-3 aqueous solution of a base.

Which acid–base pair has the highest pH at the equivalence point?

  A  

CH3COOH and NaOH

  B  

CH3COOH and NH3

  C  

HCl and NaOH


  D  

HCl and NH3

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