Acid rain contains sulfuric acid and can cause lakes to become acidic. Acidic lakes may be treated with powdered limestone, impure CaCO3, to neutralise the acidity forming calcium sulfate. If large lumps of limestone are used, instead of the powder, the reaction starts but soon stops, leaving most of the limestone unreacted. Which statement explains why the reaction starts but soon stops?
A) A layer of insoluble calcium sulfate forms on the surface of the lumps.
B) Limestone only contains small amounts of calcium carbonate.
C) Powdered limestone is more reactive than lumps of limestone.
D) The acid reacts with the calcium sulfate instead of the calcium carbonate.
In this video, we will go through the general rules of solubility for common salts to include nitrates, chlorides (including silver and lead), sulfates (including barium, calcium and lead), carbonates, hydroxides, salts of Group I cations and ammonium salts. We will also revise the chemical reaction an acid can undergo- with metals, bases and carbonates.
GCE O level, Singapore, 2014/P1/Q29
Topic: Acids and Bases, Salts, O Level Chemistry, Singapore
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