Which of the following equations is correctly balanced for the reaction between solid magnesium nitride and water to produce solid magnesium hydroxide and ammonia gas?
Show the answer and explanation
Correct answer
A. Mg3N2(s) + 6H2O(l) → 3Mg(OH)2(s) + 2NH3(g)
Principle or equation
A balanced chemical equation must have the same number of each type of atom on both sides. The correct formulas for reactants and products must be used.
Why this answer is correct
Write the unbalanced equation: Mg3N2 + H2O → Mg(OH)2 + NH3. Balance Mg: 3 Mg on left, so 3 Mg(OH)2 on right. Balance N: 2 N on left, so 2 NH3 on right. Now count H and O: right side has 3×2 = 6 OH groups (6 O, 6 H) plus 2×3 = 6 H from NH3, total 12 H and 6 O. Left side needs 6 H2O to provide 6 O and 12 H. Balanced: Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3.
Example
For Mg3N2 + H2O, the balanced equation is Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3, as verified by atom counts.
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