Question

Two gas bulbs are connected by a thin tube. Calculate the partial pressure of helium after the connective valve is opened at a constant temperature of ${27}^{\circ }C$.

• A. $1atm$
• B. $0.328atm$
• C. $1.64atm$
• D. $0.166atm$

Answer 1

Answer: (D)

$0.166atm$

$n_{He}=\frac{PV}{RT}=\frac{0.63\times 1.2}{0.0821\times 300}=0.03$
$n_{Ne}=\frac{2.8\times 3.4}{0.0821\times 300}=0.39$
$x_{He}=\frac{n_{He}}{n_{He}+n_{Ne}}=\frac{0.03}{0.03+0.39}=0.0714$
Total pressure after connecting the bulbs will be:
$P_1{V}_2+P_2{V}_2=P_R(V_1+V_2)$
$0.63\times 1.2+2.8\times 3.4=P_R(1.2+3.4)$
$P_R=2.33atm$
$P_{He}=x_{He}\times P_R=0.0714\times 2.33=0.166atm$