Analysis shows that nickel oxide has the formula $\mathrm{Ni}_{0.98} \mathrm{O}_{1.00}$. The fractions…
Analysis shows that nickel oxide has the formula $\mathrm{Ni}_{0.98} \mathrm{O}_{1.00}$. The fractions $\mathrm{Ni}^{2+}$ and $\mathrm{Ni}^{3+}$ ions in the crystal are ......
$\mathrm{Ni}^{2+}=98 \%$ and $\mathrm{Ni}^{3+}=2 \%$
$\mathrm{Ni}^{2+}=2 \%$ and $\mathrm{Ni}^{3+}=98 \%$
$\mathrm{Ni}^{2+}=4 \%$ and $\mathrm{Ni}^{3+}=96 \%$
$\mathrm{Ni}^{2+}=96 \%$ and $\mathrm{Ni}^{3+}=4 \%$
Solution
It is given that, nickel oxide has the formula as $\mathrm{Ni}_{0.98} \mathrm{O}_{1.00}$.
As per the formula, there are $98 \mathrm{Ni}$ ions for 100 oxide ions. Out of $98 \mathrm{Ni}$ ions, let $x$ ions be in +2 oxidation state.
$(98-x)$ ions will be in +3 oxidation state.
Oxide ion has -2 charge.
To maintain electrical neutrality, total positive charge on cations = total negative charge on anions.
$
\begin{aligned}
2 x+3(98-x)+100(-2) & =0 \\
x & =94
\end{aligned}
$
Fraction of $\mathrm{Ni}^{2+}$ ions $=\frac{94}{98}=0.96$
Fraction of $\mathrm{Ni}^{3+}$ ions $=\frac{4}{98}=0.04$
Hence, the fractions of nickel that exists as $\mathrm{Ni}^{2+}$ and $\mathrm{Ni}^{3+}$ are $\mathrm{Ni}^{2+}=96 \%$ and $\mathrm{Ni}^{3+}=4 \%$ respectively