Hydrogen Ques 11
11. The hydride ion, $\mathrm{H}^{-}$, is a stronger base than the hydroxide ion, $\mathrm{OH}^{-}$. Which one of the following reactions will occur if sodium hydride $(\mathrm{NaH})$ is dissolved in water?
[1997]
(a) $\mathrm{H}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\mathrm{I}) \rightarrow \mathrm{H}_3 \mathrm{O}^{-}(\mathrm{aq})$
(b) $\mathrm{H}^{-}(aq )+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_2$ (g)
(c) $\mathrm{H}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow$ $ \mathrm{OH}^{-}(\mathrm{aq})+2 \mathrm{H}^{+}(\mathrm{aq})+2 \mathrm{e}^{-} $
(d) $\mathrm{H}^{-}(aq )+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow$ reaction
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Answer:
Correct Answer: 11.(b)
Solution: (b) $\underset{\text { base 1 }}{\mathrm{H}^{-}(\mathrm{aq})}+\underset{\text { acid 1 }}{\mathrm{H}_2 \mathrm{O}(\mathrm{l})} \longrightarrow \underset{\text { base } 2}{\mathrm{OH}^{-}(\mathrm{aq})}+\underset{\text { acid2 }}{\mathrm{H}_2(\mathrm{~g})}$
In this reaction $\mathrm{H}^{-}$ acts as bronsted base as it accepts one proton $(\mathrm{H}^{+})$ from $\mathrm{H}_2 \mathrm{O}$ to form $\mathrm{H}_2$.
BETA
