When calcium metal is placed in water, a single-displacement reaction occurs. Which of the following is a balanced equation to describe this reaction?

Question

Quizplus · Accepted Answer

This reaction involves a single-displacement reaction, where calcium replaces hydrogen in water to form calcium hydroxide and hydrogen gas. The balanced equation for this reaction is: Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g). Option E represents this reaction with the correct stoichiometry, although it is written in a slightly different form. Option A is incorrect because it shows the formation of water as a gas, which is not correct. Option B is incorrect because it shows the formation of calcium oxide instead of calcium hydroxide. Option C is incorrect because it shows calcium oxide as being soluble in water, which it is not. Option D is incorrect because it shows that two calcium atoms and two water molecules are needed to form one calcium hydroxide molecule, which is not correct.

When Calcium Metal Is Placed in Water, a Single-Displacement Reaction