Question

$158.5g$ of chloride occupies a volume of $22.4L$ at STP. The percentage of chlorine in this chloride is $44.71\%$. The atomic weight and valency of the element is

• A. 88,2
• B. 88,1
• C. 71,2
• D. 71,1

Answer 1

Answer: (A)

Molecular weight of chloride $=158.5$

Let the formula of chloride is $MC{l}_x$.

Let the equivalent weight of metal $M$ is $Y$.

Then, molecular weight of $MC{l}_x=y\times x+x\times 35.5=158.5$

Equivalent weight of an element is the weight that combines with $35.5g$ of chlorine.

Equivalent weight of $M=\frac{55.29}{44.71}\times 35.5=44$

$44\times x+35.5\times x=158.5$

$\Rightarrow x=2$

Atomic weight of element, $M=44\times 2=88$

Valency $=2$

Alternatively, amount of chlorine in chloride

$=158.5\times \frac{44.71}{100}=70.8g$

i.e, $\frac{70.8}{35.5}\approx 2mol$

$\therefore$ Atomic weight of element $M=158.5-70.8$

$=87.6\approx 88$

Formula is $MC{l}_2$, valency $=2$