Solved: Limescale, $CaCO_3$ (s), can be removed from water kettles by using vinegar, a... [IB Chemistry]

Question

SLPaper 2

Limescale, $CaCO_3$ (s), can be removed from water kettles by using vinegar, a dilute solutionof ethanoic acid, $CH_3COOH$ (aq).

Predict, giving a reason, a difference between the reactions of the same concentrations of hydrochloric acid and ethanoic acid with samples of calcium carbonate.

[2]

Verified

Solution

slower rate with ethanoic acid

smaller temperature rise with ethanoic acid

1 mark

$[H^+]$ lower

ethanoic acid is partially dissociated

ethanoic acid is weak

1 mark

Accept experimental observations such as “slower bubbling” or “feels less warm”.

2 marks in total

Dissolved carbon dioxide causes unpolluted rain to have a pH of approximately 5, but other dissolved gases can result in a much lower pH. State one environmental effect of acid rain.

[1]

Verified

Solution

Any one of:

corrosion of materials/metals/carbonate materials

destruction of plant/aquatic life

«indirect» effect on human health

Accept “lowering pH of oceans/lakes/waterways”.

1 mark max

Limescale, $CaCO_3$ (s), can be removed from water kettles by using vinegar, a dilute solutionof ethanoic acid, $CH_3COOH$(aq).

Related topics