Question

Nickel oxide has the formula $Ni{O}_{0.98}{O}_{1.00}$ What fractions of nickel exist as $N{i}^{2+}$ and $N{i}^{3+}$ ion?

• A. $N{i}^{2+}=64\%$ and $N{i}^{3+}=36\%$
• B. $N{i}^{2+}=96\%$ and $N{i}^{3+}=4\%$
• C. $N{i}^{2+}=25\%$ and $N{i}^{3+}=75\%$
• D. $N{i}^{2+}=33\%$ and $N{i}^{3+}=67\%$

Answer 1

Answer: (B)

$98Ni$ atoms are associated with $100$ O-atoms
Out of $98Ni$ atoms, suppose Ni present as $N{i}^{2+}=x$
Then Ni present as $N{i}^{3+}=98-x$
Total charge on $xN{i}^{2+}$ and $(98-x)N{i}^{3+}$ + should be equal to charge on $100O^{2-}$ ions
Hence, $x\times 2+(98-x)\times 3=100\times 2$
or $2x+294-3x=200$
or $x=94$
$\therefore$ Fraction of $Ni$ present as $N{i}^{2+}=\frac{94}{98}\times 100=96\%$
Fraction of $Ni$ present as $N{i}^{3+}=\frac{4}{98}\times 100=4\%$