Q: If a gas sample is collected over water, which equation should be used to determine the pressure of the dry gas?

$P_{\text{gas}} = P_{\text{total}} - P_{\text{H}_2O}$

Q: Which of the following is the correct formula for the rate of effusion of two gases according to Graham's Law?

$\dfrac{\text{rate}_1}{\text{rate}_2} = \sqrt{\dfrac{M_2}{M_1}}$

Question 1

Which of the following best describes the relationship between pressure and volume for a gas at constant temperature, according to Boyle's Law?

Accepted Answer

Pressure and volume are inversely proportional.

Question 2

A sample of gas occupies 22.4 L at STP. If the pressure is doubled and the temperature is kept constant, what will be the new volume of the gas?

Accepted Answer

$11.2\ \mathrm{L}$

Question 3

Which equation correctly represents the Ideal Gas Law?

Accepted Answer

$PV = nRT$

Question 4

A 1.00 L sample of gas is collected at $25^\circ\mathrm{C}$ and $1.25$ atm. What is the pressure of the gas (in mm Hg) at $200^\circ\mathrm{C}$ if the volume is $4.00$ L?

Accepted Answer

$95\ \mathrm{mm\ Hg}$

Question 5

Which statement about diffusion and effusion is correct according to Graham's Law?

Accepted Answer

Lighter gases diffuse and effuse more rapidly than heavier gases.

Question 6

A mixture of gases contains $0.75$ mol $N_2$, $0.22$ mol $O_2$, and $0.60$ mol $CO_2$. If the total pressure of the mixture is $1.86$ atm, what is the partial pressure of $O_2$?

Accepted Answer

$0.37\ \mathrm{atm}$

Question 7

Which of the following is the correct definition of mole fraction ($x_A$) for component A in a mixture?

Accepted Answer

$x_A = \dfrac{n_A}{n_{total}}$

Question 8

If the density ($d$) of a gas is $0.72\ \mathrm{g/L}$ at $90.0^\circ\mathrm{C}$ and $380.0\ \mathrm{mm\ Hg}$, what is the molar mass ($M$) of the gas? Use the formula $M = \dfrac{dRT}{P}$.

Accepted Answer

$56.0\ \mathrm{g/mol}$

Question 9

Which of the following best explains why the pressure inside a barometer is measured in millimeters of mercury ($\mathrm{mm\ Hg}$)?

Accepted Answer

The height of the mercury column directly reflects atmospheric pressure.

Question 10

A gas sample has a volume of $2.5\ \mathrm{L}$ at $30^\circ\mathrm{C}$ and $720\ \mathrm{Torr}$. What will be the volume of the gas at $22^\circ\mathrm{C}$ and $760\ \mathrm{Torr}$?

Accepted Answer

$2.2\ \mathrm{L}$

Question 11

Which of the following is true about the total pressure of a mixture of gases according to Dalton's Law?

Accepted Answer

The total pressure is equal to the sum of the partial pressures of each gas.

Question 12

A sealed container with gas at $2.00$ atm and $25^\circ\mathrm{C}$ is heated to $75^\circ\mathrm{C}$. What will be the new pressure inside the container?

Accepted Answer

$2.34\ \mathrm{atm}$

Question 13

Which of the following is NOT a correct application of the combined gas law?

Accepted Answer

Finding the number of moles of a gas when only pressure and volume are known.

Question 14

Which of the following statements about standard temperature and pressure (STP) is correct?

Accepted Answer

STP is defined as $0^\circ\mathrm{C}$ and $1$ atm.

Question 15

A gas sample has a density of $0.800\ \mathrm{g/L}$ at $338$ Torr and $45^\circ\mathrm{C}$. What is the molar mass of the gas? (Use $M = \dfrac{dRT}{P}$, $R = 0.08206\ \mathrm{L\ atm\ mol^{-1}\ K^{-1}}$)

Accepted Answer

$22.4\ \mathrm{g/mol}$

Question 16

Which of the following best describes the effect of increasing temperature on the vapor pressure of a liquid?

Accepted Answer

Vapor pressure increases as temperature increases.

Question 17

If a gas sample is collected over water, which equation should be used to determine the pressure of the dry gas?

Accepted Answer

$P_{	ext{gas}} = P_{	ext{total}} - P_{	ext{H}_2O}$

Question 18

Which of the following is the correct formula for the rate of effusion of two gases according to Graham's Law?

Accepted Answer

$\dfrac{	ext{rate}_1}{	ext{rate}_2} = \sqrt{\dfrac{M_2}{M_1}}$

Question 19

A gas sample is heated from $300\ \mathrm{K}$ to $600\ \mathrm{K}$ at constant pressure. What happens to the volume of the gas?

Accepted Answer

The volume doubles.

Gases: Properties, Laws, and Calculations – Study Notes for General Biology

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