In this worksheet, we will practice calculating the pressure, temperature, and volume of an ideal gas using pV = NkT (the ideal gas law).

**Q1: **

The number
density of gas molecules is defined as the number of molecules present per unit volume. At a certain location in the space
above Earth, the number density is m^{−3} and the
atmospheric pressure at that location is N/m^{2}.
What is the temperature at this location?

**Q2: **

Airtight bags containing food that are taken to high elevations become puffed up because the air inside the bags has expanded. A bag of pretzels was packed at a pressure of 1.00 atm and a temperature of . The bag is taken to a summer picnic in Santa Fe, New Mexico, where the air temperature is . The volume of the air in the bag is 1.24 times its volume when packed. What is the pressure of the air at the picnic?

**Q4: **

A company advertises that it delivers helium at a gauge pressure of Pa in a cylinder of volume 43.8 L. How many balloons can be inflated to a volume of 4.00 L with that amount of helium? Assume the pressure inside the balloons is Pa and the temperature in the cylinder and the balloons is .

- A
- B
- C
- D
- E

**Q5: **

A bicycle tire contains 2.00 L of gas at an absolute pressure of
N/m^{2}
and a temperature of .
An amount of gas that has a volume of cm^{3}
at atmospheric pressure is released from the tire,
having negligible effect on the tire’s temperature and volume.
What is the pressure of the gas in the tire after the gas is removed?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

**Q6: **

A gas-filled incandescent light bulb is manufactured so that the gas inside the bulb is at atmospheric pressure when the bulb has a temperature of 20.0℃. Find the gauge pressure inside such a bulb when its average temperature is 60.0℃, neglecting any change in volume due to thermal expansion or gas leaks.

**Q7: **

A high-pressure gas cylinder contains
50.0 L of toxic
gas at a pressure of
N/m^{2}
and a temperature
of 25.0℃.
The cylinder is cooled to dry ice temperature
to reduce the leak rate and pressure so that it can be safely repaired.

What is the final pressure in the tank, assuming a negligible amount of gas leaks while being cooled and that there is no phase change?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

What is the final pressure if one tenth of the gas escapes?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

To what temperature must the tank be cooled to reduce the pressure to 1.00 atm (assuming the gas does not change phase and that there is no leakage during cooling)?

**Q8: **

One process for decaffeinating coffee uses carbon dioxide
at a molar density of mol/m^{3} and a temperature of 60.0℃.
The van der Waals constants for carbon dioxide are and . Using the van der Waals equation, find the pressure of
at that temperature and density.

- A Pa
- B Pa
- C Pa
- D
- E Pa

**Q9: **

A tank with a volume of 6.75 m^{3} contains
mol of compressed oxygen.
Determine the gauge pressure inside the tank if the root-mean-square speed of the
oxygen molecules is 524 m/s.
Use a value of 32.0 g/mol for the molar mass of
molecular oxygen.

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

**Q10: **

A mole of dry air consists of nitrogen, oxygen, and argon, with trace amounts of other gases. A tank of compressed dry air at a temperature of 293 K has a volume of 1.76 cubic feet. The compressed air has a gauge pressure of pounds per square inch. How many moles of oxygen does the compressed air contain?

**Q11: **

An airplane passenger’s stomach contains
170 cm^{3} of air just before the plane takes off
from a sea-level airport. What will the volume of air in her stomach be during the flight if the airplane’s cabin pressure
is N/m^{2}?

- A
107 cm
^{3} - B
480 cm
^{3} - C
208 cm
^{3} - D
207 cm
^{3} - E
430 cm
^{3}

**Q12: **

The deep space between galaxies is not a complete vacuum.
The intergalactic medium can be modeled as an ideal gas with a density of various molecular and sub-molecular
scale particles of 204 particles/m^{3}, at an average temperature of
3.4 K.

What pressure is produced by the intergalactic medium?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

What volume is occupied by 1.00 mol of intergalactic medium particles?

- A
m
^{3} - B
m
^{3} - C
m
^{3} - D
m
^{3} - E
m
^{3}

What is the side length of a cube that has the volume required to contain 1.00 mol of intergalactic medium particles?

**Q13: **

The air inside a hot-air balloon has a temperature of 387 K and a pressure of 103.3 kPa, the same as that of the air outside. Using the molar composition of air as , , and , find the density of the air inside the balloon. Use a value of 28.0 g/mol for the molar mass of , 32.0 g/mol for the molar mass of , and 39.3 g/mol for the molar mass of .

**Q15: **

2.25 kg of steam is contained in a region with a volume of
0.448 m^{3} and at
a pressure of Pa.
The steam can be modeled as having a molar mass of 18.0 g/mol.

If the steam is modeled as an ideal gas, what is the steam’s temperature?

The van der Waals constants for water
are Pa⋅m^{6}/mol^{2} and
m^{3}/mol.
If the van der Waals equation of state
is used to calculate the temperature of the steam, what is the calculated temperature?

**Q16: **

Treating air as if it was an ideal gas and a single substance, calculate the number of moles of air that would be contained in the 2.00 L volume of air in the lungs of the average person. Assume the air to be at atmospheric pressure and a temperature of .

- A
- B
- C
- D
- E

**Q17: **

A tire with a volume of 35.0 L contains 4.86 mol of a gas at a temperature of . An additional 1.25 L of gas is added to the tire, increasing its pressure while the temperature and volume of the gas remain constant.

What is the gauge pressure in the tire before the additional gas is added?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

What is the gauge pressure in the tire after the additional gas is added?

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

**Q18: **

When an air bubble rises from the bottom to the top of a freshwater lake, its volume increases by . If the temperatures at the bottom and the top of the lake are 4.0 and 10℃, respectively, how deep is the lake?

**Q19: **

A car’s tires have a gauge pressure of
N/m^{2} when at
a temperature of . What is the gauge pressure
of the tires at a temperature of ?
Assume the tires have not gained or lost any air.

- A Pa
- B Pa
- C Pa
- D Pa
- E Pa

**Q20: **

In a common demonstration, a hard-boiled egg is pushed through the neck of a glass bottle that is noticeably narrower than the egg’s width. A bottle used in such a demonstration has a volume of 0.750 L and the temperature inside the bottle is maintained at . The pressure inside the bottle is maintained at a constant 1.00 atm. An egg is then placed on the bottle’s neck and the bottle is cooled until its internal temperature is . The pressure inside the bottle falls as the air inside the bottle reduces in temperature and the greater external air pressure pushes the egg through the bottle’s neck.

How many moles of air does the bottle contain?

What is the air pressure inside the bottle after it has been cooled, just before the egg starts to move down the bottle’s neck?

**Q21: **

A gas in a container that has a volume of
2.45 L is at a temperature
of 42℃
and a pressure of N/m^{2}.
How many moles of gas are in the container?

**Q22: **

A rigid vessel is maintained at a pressure of 10 MPa and a temperature of 300℃. The vessel contains steam that has a mass of 0.80 kg. What is the volume of the vessel?