Q: Convert a pressure of 1.25 atm to mm Hg.

$$1.25 \times 760 = 950 mm Hg$$

Q: Which equation is used to calculate the density of a gas at STP?

$$\text{Density} = \frac{\text{molar mass}}{\text{molar volume}}$$

Question 1

Which statement best describes why gases are compressible?

Accepted Answer

Gas particles are far apart, so most of the volume is empty space.

Question 2

A barometer measures atmospheric pressure using mercury. If the atmospheric pressure increases, what happens to the height of the mercury column?

Accepted Answer

The height of the mercury column increases.

Question 3

Convert a pressure of 1.25 atm to mm Hg.

Accepted Answer

$$1.25 	imes 760 = 950 mm Hg$$

Question 4

Which of the following correctly expresses Boyle's Law?

Accepted Answer

$$PV = k$$

Question 5

A sample of gas at 2.00 atm and 3.00 L is allowed to expand to 6.00 L at constant temperature. What is the final pressure?

Accepted Answer

$$1.00$$ atm

Question 6

According to Charles's Law, what happens to the volume of a gas if the temperature (in Kelvin) is doubled at constant pressure?

Accepted Answer

The volume is doubled.

Question 7

A balloon contains 0.50 mol of gas at 1 atm and 273 K. If the amount of gas is increased to 1.00 mol at constant temperature and pressure, what happens to the volume?

Accepted Answer

The volume is doubled.

Question 8

What is the volume occupied by 2.00 mol of an ideal gas at STP?

Accepted Answer

$$44.82 L$$

Question 9

Which equation is used to calculate the density of a gas at STP?

Accepted Answer

$$	ext{Density} = \frac{	ext{molar mass}}{	ext{molar volume}}$$

Question 10

A gas has a molar mass of 32 g/mol. What is its density at STP?

Accepted Answer

$$1.43 g/L$$

Question 11

In the decomposition of sodium azide ($$2NaN_3 (s) \rightarrow 2Na(s) + 3N_2 (g)$$), how many moles of $$N_2$$ are produced from 65.0 g of $$NaN_3$$?

Accepted Answer

$$3.00$$ mol

Question 12

Which law states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas?

Accepted Answer

Dalton's Law of Partial Pressures

Question 13

A mixture contains 2 mol $$O_2$$ and 3 mol $$N_2. $$What is the mole fraction of $$O_2$$?

Accepted Answer

$$0.40$$

Question 14

According to the kinetic-molecular theory, what is true about the collisions between gas particles?

Accepted Answer

Collisions are elastic and do not result in energy loss.

Question 15

Which formula gives the root mean square speed ($$u_{rms}) of a $$gas molecule?

Accepted Answer

$$u_{rms} = \sqrt{\frac{3RT}{M}}$$

Question 16

If the temperature of a gas sample is increased, what happens to the distribution of molecular speeds?

Accepted Answer

The distribution flattens and the maximum shifts to higher speeds.

Question 17

What is the mean free path of a gas molecule?

Accepted Answer

The average distance a molecule travels between collisions.

Question 18

According to Graham's Law, how does the rate of effusion of a gas relate to its molar mass?

Accepted Answer

Rate of effusion is inversely proportional to the square root of molar mass.

Question 19

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

Accepted Answer

Correction for molecular volume and intermolecular attractions.

Gases: Their Properties and Behavior – Chapter 10 Study Notes

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