Q: A 56 kg person stands on a pointed heel with an area of $$0.45 \mathrm{~cm}^2. $$What is the pressure exerted on the floor in pascals ($$\mathrm{Pa}$$)? (Assume $$g = 9.81 \mathrm{~m/s}^2)$$

$$1.22 \times 10^6$~\mathrm{Pa}$$

Question 1

Which of the following statements best explains why gases are easily compressible compared to solids and liquids?

Accepted Answer

Gases consist of particles that are far apart, so the volume can decrease significantly under pressure.

Question 2

A 56 kg person stands on a pointed heel with an area of $$0.45 \mathrm{~cm}^2. $$What is the pressure exerted on the floor in pascals ($$\mathrm{Pa}$$)? (Assume $$g = 9.81 \mathrm{~m/s}^2)$$

Accepted Answer

$$1.22 	imes 10^6$~\mathrm{Pa}$$

Question 3

Which property is NOT characteristic of a gas?

Accepted Answer

Gases have definite volume.

Question 4

Given the equation for pressure $$P = \frac{F}{A}$$, which change will result in a higher pressure exerted by a gas on the walls of its container?

Accepted Answer

Decreasing the area while keeping force constant.

Question 5

A sample of gas at constant temperature is compressed from $$4.0~\mathrm{L} to$$ $$2.0~\mathrm{L}. If $$the initial pressure was $$1.0~\mathrm{bar}$$, what is the final pressure?

Accepted Answer

$$2.0~\mathrm{bar}$$

Question 6

Which of the following best describes the relationship between temperature and volume for a gas at constant pressure?

Accepted Answer

Volume is directly proportional to temperature.

Question 7

A sealed container of oxygen gas has a volume of $$269~\mathrm{L} at$$ $$27.3^\circ\mathrm{C}$$ ($$300.5~\mathrm{K}). $$What will the volume be if the temperature is lowered to $$-2.4^\circ\mathrm{C}$$ ($$270.8~\mathrm{K}$$), assuming constant pressure?

Accepted Answer

$$242~\mathrm{L}$$

Question 8

Which law describes the relationship between the amount of gas (in moles) and its volume at constant temperature and pressure?

Accepted Answer

Avogadro's Law

Question 9

A $$22.56~\mathrm{L}$$ sample of $$N_2$$ gas at $$20^\circ\mathrm{C}$$ and $$83.3~\mathrm{kPa} is $$given. What is the mass of $$N_2 in $$the sample? ($$M_{N_2$} = 28.02~\mathrm{g/mol}$$, $$R = 8.314~\mathrm{L~kPa~K$$^{-1}$$~$$mol^{-1}$$})$$

Accepted Answer

$$2.19~\mathrm{g}$$

Question 10

Which of the following is the correct value for the universal gas constant $$R$$ when pressure is in bar, volume in liters, and temperature in kelvin?

Accepted Answer

$$0.08314~\mathrm{L~bar~$$mol^{-1}$$~K$$^{-1}$$}$$

Question 11

A $$3.15~\mathrm{L}$$ sample of neon gas at $$0.951~\mathrm{bar} is $$compressed to $$1.292~\mathrm{bar} at $$constant temperature. What is the new volume?

Accepted Answer

$$2.32~\mathrm{L}$$

Question 12

According to the kinetic molecular theory, what happens to the average kinetic energy of gas molecules when the temperature is doubled (in kelvin)?

Accepted Answer

It is doubled.

Question 13

Which of the following gases will have the highest root mean square velocity ($$u_{rms}) at $$the same temperature?

Accepted Answer

Helium ($$He)$$

Question 14

A mixture contains three gases: A, B, and C. If the total pressure is $$6~\mathrm{bar}$$ and the mole fraction of gas C is $$0.25$$, what is the partial pressure of gas C?

Accepted Answer

$$1.5~\mathrm{bar}$$

Question 15

A $$75.0~\mathrm{mL}$$ sample of argon gas is at STP. What is the mass of argon in the sample? ($$M_{Ar} = 39.95~\mathrm{g/mol}$$, $$1~\mathrm{mol} at $$STP = $$22.7~\mathrm{L})$$

Accepted Answer

$$0.132~\mathrm{g}$$

Question 16

Which of the following best explains why the ideal gas law tends to overestimate the pressure of a real gas at low temperatures?

Accepted Answer

Intermolecular attractions reduce the number of collisions with the container walls.

Question 17

Which correction does the van der Waals equation introduce to the ideal gas law?

Accepted Answer

It accounts for the finite volume of gas particles and intermolecular forces.

Question 18

A $$1.00~\mathrm{mol}$$ sample of $$Cl_2$$ gas is confined to a $$2.00~\mathrm{L}$$ container at $$273~\mathrm{K}. $$Using the van der Waals equation ($$a = 6.579~\mathrm{L^2$~bar~$$mol^{-2}$$}$$, $$b = 0.0562~\mathrm{L~$$mol^{-1}$$}$$), which of the following is closest to the pressure exerted by the gas?

Accepted Answer

$$10.8~\mathrm{bar}$$

Chapter 5: Gases – Properties, Pressure, and Measurement

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