Question

A 265 ml flask contains pure helium at a pressure of 749 torr. A 455 ml flask contains pure argon at a pressure of 729 torr. The two flasks are connected through stopcock and are at the same temperature. What is the pressure once the stopcock is opened?
a. 736 Torr
b. 276 Torr
c. 461 Torr
d. 250 Torr
e. 449 Torr

Answer 1

Answer:

a. $P_T=736.4torr$

Explanation:

Hello,

By using Boyle's law, one computed the final pressure for both helium and argon as shown below:

$P_{2,He}=\frac{265mL*749torr}{265mL+455mL} =275.67torr\\P_{2,Ar}=\frac{455mL*729torr}{265mL+455mL} =460.69torr$

Now, by adding the resulting pressures, we compute the final pressure after the stopcock is opened:

$P_T=P_{2,He}+P_{2,Ar}=275.67torr+460.69torr\\P_T=736.4torr$

So the answer is a.

Best regards.