How would you balance the following equation: Ca+HNO3 --> Ca(NO3)2+ N2O3+ H2O?

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How would you balance the following equation: Ca+HNO3 --> Ca(NO3)2+ N2O3+ H2O?

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Answer 1 · 2016-02-11T15:47:43

By the method of half-equations: calcium metal is oxidized, and nitrogen is reduced.

Explanation:

Oxidation:

$C a (s) \to C a^{2 +} + 2 e^{-}$ $Ca(s) rarr Ca^(2+) + 2e^-$ $(i)$ $(i)$

Reduction:

$2 H N O_{3} (a q) + 4 e^{-} + 4 H^{+} \to N_{2} O_{3} + 3 H_{2} O$ $2HNO_3(aq) +4e^(-) +4H^(+) rarr N_2O_3 +3H_2O$ $(i i)$ $(ii)$

Note that dinitrogen trioxide is a metastable species, and is a mixed valence oxide of $N (I I +)$ $N(II+)$ and $N (I V +)$ $N(IV+)$ , hence an average oxidation state of $I I I +$ $III+$ .

Both $(i)$ $(i)$ and $(i i)$ $(ii)$ are balanced with respect to mass and charge (as they must be!). We add $2 \times (i) + (i i)$ $2xx(i) +(ii)$ to give:

$2 C a (s) + 2 H N O_{3} (a q) + 4 H^{+} \to 2 C a^{2 +} + N_{2} O_{3} (a q) + 3 H_{2} O (a q)$ $2Ca(s) + 2HNO_3(aq) +4H^(+) rarr 2Ca^(2+) + N_2O_3(aq) +3H_2O(aq)$

Since the source of $H^{+}$ $H^+$ is undoubtedly nitric acid, we could write:

$2 C a (s) + 6 H N O_{3} (a q) \to 2 C a {(N O_{3})}_{2} + N_{2} O_{3} (a q) + 3 H_{2} O (a q)$ $2Ca(s) + 6HNO_3(aq) rarr 2Ca(NO_3)_2 + N_2O_3(aq) +3H_2O(aq)$

Is this last equation balanced with respect to mass and charge? Do not trust my arithmetic!

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How would you balance the following equation: Ca+HNO3 --> Ca(NO3)2+ N2O3+ H2O?

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