Question

Equal weights of ethane and hydrogen are mixed in an empty container at $25^{\circ}C$. The The fraction of total pressure exerted by hydrogen is

• A. 1 : 2
• B. 1 : 1
• C. 1 : 16
• D. 15 : 16

Answer 1

Answer: (D)

Given, equal weights of ethane and hydrogen are mixed in an empty container at $25^{\circ} C$

Initial gram weight = $\overset{C_2H_6}{wg}\,\,\,\, \overset{H_2}{wg}$

Number of moles $=\frac{w}{30} \,\,\,\,\, \frac{w}{2}$

According to Henry's law,

$\frac{p_{ H _{2}}}{p_{\text {total }}}=\chi_{ H _{2}}=\frac{n_{ H _{2}}}{n_{ H _{2}}+n_{ C _{2} H _{6}}}=\frac{\frac{w}{2}}{\frac{w}{2}+\frac{w}{30}} $

$\frac{p_{ H _{2}}}{p_{\text {total }}}=\frac{\frac{w}{2}}{\frac{15 w+w}{30}}=\frac{w}{2} \times \frac{30}{16 w}=\frac{15}{16}$

So, the fraction of total pressure exerted by hydrogen is $15: 16$