Question

Choose the correct chemical equation for the given word equation.

$\mathrm{Calcium}+\mathrm{Nitrogen}\to \mathrm{Calcium}\mathrm{Nitride}$

• A. $\mathrm{Ca}+{\mathrm{N}}_2\to {\mathrm{CaN}}_2$
• B. $3\mathrm{Ca}+{\mathrm{N}}_2\to {\mathrm{Ca}}_3{\mathrm{N}}_2$
• C. $3\mathrm{Ca}+\mathrm{N}\to {\mathrm{Ca}}_3\mathrm{N}$
• D. $\mathrm{Ca}+\mathrm{N}\to \mathrm{CaN}$

Answer 1

The correct option is B

$3\mathrm{Ca}+{\mathrm{N}}_2\to {\mathrm{Ca}}_3{\mathrm{N}}_2$

The explanation for the correct option:

(B)

• Calcium is a metal whose chemical symbol is $\mathrm{Ca}$.
• Nitrogen is a diatomic gas with a chemical formula ${\mathrm{N}}_2$.
• The chemical formula of Calcium nitride is determined by the criss-cross method.
• Calcium exists as ${\mathrm{Ca}}^{2+}$ ion and Nitride exists as ${\mathrm{N}}^{3-}$.
• By swapping the charges and dropping the sign of the charges, the chemical compound of calcium nitride will become ${\mathrm{Ca}}_3{\mathrm{N}}_2.$
• $\underset{2}{\mathrm{Ca}}\searrow \swarrow \underset{3}{\mathrm{N}}$
• Thus, the chemical equation is $\underset{\mathrm{Calcium}}{3\mathrm{Ca}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrogen}}{{\mathrm{N}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Calcium}\mathrm{Nitride}}{{\mathrm{Ca}}_3{\mathrm{N}}_2\left(\mathrm{s}\right)}$

Hence, the correct option is an option(B).