Question

When 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as:

• A. NaOH + Zn → NaZnO2 + H2O
• B. 2NaOH + Zn → Na2ZnO2 + H2
• C. 2NaOH + Zn → NaZnO2 + H2
• D. 2NaOH + Zn → Na2ZnO2 + H2O

Answer 1

Answer: (B)

2NaOH + Zn → Na2ZnO2 + H2

Answer 2

Sodium hydroxide reacts with zinc to form sodium zincate ($\text{Na}_2\text{ZnO}_2$) and hydrogen gas ($\text{H}_2$). The balanced reaction is:
$2\text{NaOH} + \text{Zn} \rightarrow \text{Na}_2\text{ZnO}_2 + \text{H}_2$
This reaction demonstrates the amphoteric nature of zinc, which reacts with alkali to release hydrogen gas.