Question

Equal masses of hydrogen gas and oxygen gas are placed in a closed container at a pressure of $3.4atm$. The contribution of hydrogen gas to the total pressure is:

• A. $1.7atm$
• B. $0.2atm$
• C. $3.2atm$
• D. $3.02atm$

Answer 1

Answer: (C)

$3.2atm$

Let mass of hydrogen and oxygen be $100g$

$n_1=$ no of moles of hydrogen=$\frac{100}{2}=50$

$n_2=$ no of moles of oxygen=\cfrac {100}{32}=3.125$

Contribution of hydrogen to the total pressure means, mole fraction of hydrogen present in the mixture (partial pressure of $H_2$)

$X_4=\frac{n_{H_2}}{n_{H_2}+n_{O_2}}=\frac{50}{50+3.125}=0.94$

Contribution of hydroegn to the total pressure= $0.94\times P=0.94\times 3.4=3.2$ atm