Question

Analysis shows that nickel oxide has the formula Ni0.98O1.00. What fractions of nickel exist as Ni 2+ and Ni 3+ ions?

Answer 1

Hi there!

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Answer :

$Ni_{0.98}$ $O_{1.00}$ ;

Let $Ni^{2+}$ be '$x$', therefore, $Ni^{3+}$ will be 0.98 - x.

Total charge on compound is equal to zero.

∴ + 2x + 3(0.98 - x) - 2 = 0

⇒ 2x + 2.94 - 3x - 2 = 0

⇒ x = 0.94

∴ % of $Ni^{2+}$ = $\frac{0.94}{0.98}$ × 100 = 96%

and, % of $Ni^{3+}$ = 4%

Answer 2

formula of Nickel oxide , $N_{0.98}O_{1.00}$
ratio of Ni and O in given nickel oxide compound is 0.98 : 1.00
e.g., Ni : O = 98 : 100
so, total charge on $O^{2-}$ ion = 100 × (-2) = -200
Let number of $Ni^{2+}$ ion = x
then, number of $O^{3+}$ = 98 - x
now, x × (+2) + (98 - x) × (+3) -200 = 0
2x + 294 - 3x - 200 = 0
- x + 94 = 0 => x = 94
hence, number of $Ni^{2+}$ = 94
so, fraction of nickel exists as $Ni^{2+}$ = 94/98 = 0.959
now, number of $Ni^{3+}$ = 98 - 94 = 4
so, fraction of nickel exists as $Ni^{3+}$ = 4/98 = 0.041