Question

31.5 grams of Cl2 is collected over water at 35 C. The volume of the chlorine is 15.0 l when the water levels are equal. What is the barometric pressure? (Pressure should be in torr.)

Answer 1

Given:

mass of chlorine = 31.5 grams Cl2
temperature of water = 35 degrees C
volume of chlorine = 15 L

*water levels are equal
assume ideal gas behavior

Vapor pressure of water at 35 C = 42.2 torr

To solve for the barometric pressure, use the ideal gas equation:

PV = nRT

where P = Pgas - Pwater

(Pgas - 42.2 torr) * 15 L = 31.5g/70.9g/mol * (35 + 273) K * (760 torr * 22.4 L/298K)

solve for Pgas

Pgas = 563.36 torr

Therefore, the barometric pressure is 563.36 torr.