Q: A mixture contains equal numbers of moles of helium and neon. If the total pressure is $3.0 \text{ atm}$, what is the partial pressure of each gas?

$1.5 \text{ atm}$ \text{ for He and } 1.5 \text{ atm}$ \text{ for Ne}

Question 1

Which of the following best explains why atmospheric pressure decreases with increasing altitude?

Accepted Answer

The number of gas particles per unit volume decreases as altitude increases.

Question 2

A diver descends to a depth of 20 meters in the ocean. If the pressure increases by approximately 1 atm for every 10 meters of depth, what is the total pressure experienced by the diver at this depth?

Accepted Answer

$3 	ext{ atm}$

Question 3

Which instrument is used to measure the pressure of a gas trapped in a container, and how does it work?

Accepted Answer

A manometer; it compares the pressure of the gas to atmospheric pressure using the difference in liquid levels.

Question 4

According to Boyle's Law, what happens to the volume of a gas if the pressure is tripled, assuming temperature and amount of gas are constant?

Accepted Answer

The volume decreases to one-third of its original value.

Question 5

A balloon is moved from an ice water bath ($0^\circ 	ext{C}$) to a boiling water bath ($100^\circ 	ext{C}$) at constant pressure. What happens to the volume of the balloon?

Accepted Answer

The volume increases because the gas particles move faster and occupy more space.

Question 6

Which of the following actions will increase the volume of a gas sample, assuming all other variables are held constant?

Accepted Answer

Decreasing the pressure.

Question 7

At standard temperature and pressure (STP), what is the volume occupied by one mole of any ideal gas?

Accepted Answer

$22.4 	ext{ L}$

Question 8

Which of the following gases has the highest density at STP?

Accepted Answer

Chlorine ($	ext{Cl}_2$)

Question 9

A mixture contains equal numbers of moles of helium and neon. If the total pressure is $3.0 	ext{ atm}$, what is the partial pressure of each gas?

Accepted Answer

$1.5 	ext{ atm}$ 	ext{ for He and } 1.5 	ext{ atm}$ 	ext{ for Ne}

Question 10

Which statement about the kinetic molecular theory is correct?

Accepted Answer

The average kinetic energy of a gas particle is proportional to the temperature in kelvins.

Question 11

Which equation correctly relates the pressure, volume, temperature, and amount of an ideal gas?

Accepted Answer

$PV = nRT$

Question 12

If the temperature of a gas sample is doubled (in kelvins) at constant pressure, what happens to the volume?

Accepted Answer

The volume doubles.

Question 13

Which of the following best describes Graham’s Law of Effusion?

Accepted Answer

The rate of effusion of a gas is inversely proportional to the square root of its molar mass.

Question 14

A sample of gas is collected over water at $25^\circ 	ext{C}$ with a total pressure of $758.2 	ext{ mmHg}$. If the vapor pressure of water at this temperature is $23.7 	ext{ mmHg}$, what is the partial pressure of the dry gas?

Accepted Answer

$734.5 	ext{ mmHg}$

Question 15

Which modification did van der Waals make to the ideal gas law to account for real gas behavior at high pressures?

Accepted Answer

He added terms to account for molecular volume and intermolecular attractions.

Question 16

Which of the following is true about the root mean square velocity ($u_{rms}$) of gas molecules?

Accepted Answer

Lighter gas molecules have a higher $u_{rms}$ than heavier ones at the same temperature.

Question 17

Which of the following best describes Dalton’s Law of Partial Pressures?

Accepted Answer

The total pressure of a gas mixture is the sum of the partial pressures of its components.

Question 18

A rigid container holds a mixture of $N_2$ and $H_2$ gases that react to form $NH_3$ according to $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$. If the volume is constant and nothing is added or removed, what happens to the total pressure during the reaction?

Accepted Answer

The pressure decreases because the total number of gas molecules decreases.

Question 19

Which of the following statements about real gases is correct?

Accepted Answer

At high pressures, the volume of a real gas is greater than predicted by the ideal gas law due to the finite size of molecules.

General Chemistry: Chapter 6 – Gases (Study Notes)

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