The Solid State - Result Question 34
####34. Formula of nickel oxide with metal deficiency defect in its crystal is $Ni _{0.98} O$. The crystal contains $Ni^{2+}$ and $Ni^{3+}$ ions. The fraction of nickel existing as $Ni^{2+}$ ions in the crystal is
(a) 0.31
(b) 0.96
(c) 0.04
(d) 0.50
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Solution:
- (b) $Ni _{0.98} O=(Ni^{2+}) _{x}(Ni^{3+}) _{0.98-x}(O^{2-})_1$
Net charge $=0$
$ \begin{aligned} & {[x \times 2]+[(0.98-x) \times 3]+[-2 \times 1]=0} \\ & x=0.94 \end{aligned} $
Fraction of nickel existing as
$ Ni^{2+}=\frac{0.94}{0.98}=0.959 \approx 0.96 $
