Question

In a non-stochiometric sample of cuprons sulphide, with the composition $C{u}_{1.8}$, cupric ions are also present in the lattice. The mole % of $C{u}^{2+}$ present in the copper content of the crystal is:

• A. $99.9$%
• B. $11.11$%
• C. $88.88$%
• D. $18$%

Answer 1

The correct option is C $88.88$%

$180Cu$ atoms are associated with $100S$ atoms.

Let $x$ atoms be present as $C{u}^{+}$

Total charge on $xC{u}^{+}$ and $(180-x)C{u}^{2+}$ must be equal to total charge on $100S^{2-}$ ions.

So, $x+2(180-x)=2\times 100$

$x+360-2x=200$

$x=160$

% of $C{u}^{+}$ ions $=\frac{160}{180}\times 100=88.9$%