Question

In an experiment, it is found that $2.0769g$ of pure $X$ produces $3.6769g$ of pure $X_2{O}_5$. The number of moles of $X$ is:

• A. $0.04$
• B. $0.06$
• C. $0.40$
• D. $0.02$

Answer 1

The correct option is A $0.04$

Balanced chemical equation:-
$2X+\frac{5}{2}{O}_2\to X_2{O}_5$

$2$ moles of $X$ produces $\to$ 1 mole$X_2{O}_5$

$\frac{2.0769}{M_x}$ moles of $X$ produces $\to \frac{2.0769}{2M_x}ml{X}_2{O}_5$

Given:
$3.6769g$ of $X_2{O}_5$ is produced.

$\therefore$ moles of $X_2{O}_5=\frac{3.6769}{2M_x+5\times 16}$
$=\frac{3.679}{2M_x+80}$

$\frac{1}{2M_x}=\frac{1.77}{2M_x+80}$

$2M_x+80=3.54M_x$

$80=1.54M_x$

$\frac{80}{1.54}=M_x$

$\Rightarrow M_x=51.94g/ml$

$\therefore$Moles of $x$ present $=\frac{2.0769}{51.94}=0.4moles$