# Worksheet: Vapor Pressure and Relative Humidity

In this worksheet, we will practice defining a vapor's relative humidity as the ratio of the partial pressure of the vapor to its equilibrium vapor pressure.

Q1:

On a warm day when the air temperature is , a metal can is slowly cooled by adding bits of ice to liquid water in it. Condensation first appears when the can reaches . What is the relative humidity of the air? Given the vapor pressure of water at is 1,705 Pa and at is 4,243 Pa.

• A
• B
• C
• D
• E

Q2:

Air is oxygen.

Find the minimum atmospheric pressure that gives a relatively safe partial pressure of oxygen of 0.16 atm.

What is the minimum pressure that gives a partial pressure of oxygen above the quickly fatal level of 0.060 atm?

Q3:

Find the density of air at a pressure of 1.00 atm and a temperature of , assuming that air is N2, O2, and Ar.

Find the density of the atmosphere on Venus, assuming that the atmosphere is CO2 and N2, with a temperature of 737 K and a pressure of 92.0 atm.

Q4:

Per mole, the atmosphere of a planet consists of nitrogen, oxygen, and hydrogen. In modeling the planet’s atmosphere, use a value of 28.0 g/mol for the molar mass of N2, 32.0 g/mol for the molar mass of O2, and 2.02 g/mol for the molar mass of H2.

What is the mass of the nitrogen in 1.0 mol of this planet’s atmosphere?

The atmosphere of this planet is mixed with pentane in a ratio of by mass. Find the partial pressure of pentane in this mixture at an overall pressure of 2.50 atm. Use a value of 72.2 g/mol for the molar mass of pentane.

Q5:

What are the temperature and pressure of water at the triple point?

• A273 K and 1,000 kPa
• B373 K and 101 kPa
• C173 K and 611 kPa
• D273 K and 0.611 kPa
• E0 K and 0.611 kPa

Q6:

In a system, a water vapor mixture is at equilibrium at a temperature of 473 K. What is the pressure of the system?

Q7:

A rigid vessel contains water vapor mixture in equilibrium at a pressure of 4.76 MPa. What is the temperature of the system?

Q8:

A system contains water at a pressure of 4 MPa and a temperature of . What is the phase of this water?

• ASolid-liquid mixture
• BSolid
• CLiquid-vapor mixture
• DVapor
• ELiquid

Q9:

A system contains water at a pressure of 4 MPa and a temperature of . What is the phase of this water?

• ALiquid-vapor mixture
• BSolid
• CSolid-liquid mixture
• DVapor
• ELiquid

Q10:

A rigid vessel with a volume of 200 m3 contains a saturated liquid-vapor mixture with a vapor quality of . The temperature of the vessel is maintained at 393 K. What is the total mass of the liquid-vapor mixture inside the vessel?