Warm-up 1/15 D2 (Antacids) Practice Problems
Two substances commonly used in antacid tablets are magnesium hydroxide
and aluminium hydroxide.
(a) State an equation to represent a neutralization reaction with one of
the above antacids.
(1)
(b) State and explain whether 0.1 mol of magnesium hydroxide is more
effective or less effective than 0.1 mol of aluminium hydroxide.
(1)
(c) Suggest why compounds such as sodium hydroxide or potassium
hydroxide cannot be used as an antacid.
(1)
(d) Explain why alginates and dimethicone are often included in
antacid tablets.
Alginates:
Dimethicone:
(2)
(Total 5 marks)
(a)
Al(OH)3 + 3HCl → AlCl3 + 3H2O / Mg(OH)2 + 2HCl → MgCl2 + 2H2O;
Accept ionic equations.
(b)
less effective and (magnesium hydroxide) 2/0.2 mol OH– ions
available as compared to (aluminium hydroxide) 3/0.3 mol OH–
ions for neutralization / neutralizes 2H+/0.2 mol acid as compared
to 3H+/0.3 mol acid;
Do not accept aluminium hydroxide can neutralize more acid.
(c)
strong base / corrosive / harmful to the body;
(d)
Alginates:
provide a neutralizing layer on top of the stomach contents / to
prevent acid rising up the esophagus / prevents acid reflux/heartburn;
Dimethicone:
as an anti-foaming agent / to prevent flatulence/gas/bloating;
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