Question

A stop-cock connecting two bulbs of $3L$ and $5L$, containing an ideal gas at $10$ atm and $12$ atm respectively, is opened. What is the final pressure, if the two bulbs are opened at the same temperature?

• A. $22.6$ atm
• B. $11.3$ atm
• C. $9$ atm
• D. $12$ atm

Answer 1

Answer: (B)

$11.3$ atm

Bulb 1, $P_1{V}_1=n_{1}RT$
Bulb 2, $P_2{V}_2=n_{2}RT$

On mixing, $P_1{V}_1+P_2{V}_2=(n_1+n_2)RT$.......(i)

After opening, let the pressure be P.

$P(V_1+V_2)=(n_1+n_2)RT$.......(ii)

From (i) and (ii), $P_1{V}_1+P_2{V}_2=P(V_1+V_2)$

$⟹10\times 3+12\times 5=P\left(8\right)$

$P=\frac{90}{8}=11.3atm$