Question

A 255-mL flask contains pure helium at a pressure of 746 torr . A second flask with a volume of 475 mL contains pure argon at a pressure of 726 torr . If the two flasks are connected through a stopcock and the stopcock is opened, what is the partial pressure of helium? If the two flasks are connected through a stopcock and the stopcock is opened, what is the partial pressure of argon?

If the two flasks are connected through a stopcock and the stopcock is opened, what is the total pressure?

Answer 1

pHe = 261 torr

pAr = 472 torr

P = 733 torr

Step-by-step explanation:

The final volume for both gases is the same: V₂ = 255 mL + 475 mL = 730 mL

We can find the final partial pressure of each gas using Boyle's law.

He

P₁ × V₁ = P₂ × V₂

P₂ = P₁ × V₁ / V₂

P₂ = 746 torr × 255 mL / 730 mL = 261 torr

Ar

P₁ × V₁ = P₂ × V₂

P₂ = P₁ × V₁ / V₂

P₂ = 726 torr × 475 mL / 730 mL = 472 torr

The total pressure is the sum of the partial pressures.

P = 261 torr + 472 torr = 733 torr