Question 1

If a 0.18 g sample of aluminum metal is dropped into 400 mL of 6 M HCl, hydrogen gas is evolved. The hydrogen evolved is collected over water, so the gas collected is a mixture of water vapour (vapour pressure = 23.8 mm Hg) and hydrogen gas. If the external pressure is 1.02 atm and temperature is 25?C, what will be the total volume of gas collected in L?

Accepted Answer

The answer of If a 0.18 g sample of aluminum...

Question 2

The noxious gas H₂S can be used to remove the acid rain component SO₂ from factory emissions by the Claus Process. What volume of H₂Sin litres at STP will be needed to remove 2.00 kg of SO₂? 2 H₂S₍_g) + SO_2(g) $\rarr$ 3 S_(s) + 2 H₂O_(l)

Accepted Answer

The balanced equation shows that 2 moles of H₂S are needed to react with 1 mole of SO₂. The molar mass of SO₂ is 64 g/mol, so 2.00 kg of SO₂ is equal to 2.00 kg / 64 g/mol = 31.25 mol. Therefore, 2 * 31.25 = 62.5 mol of H₂S are needed. At STP, 1 mol of any gas occupies 22.4 L, so 62.5 mol of H₂S will occupy 62.5 mol * 22.4 L/mol = 1400 L.

Question 3

Consider the conversion of methane to acetylene and hydrogen gas shown in the unbalanced reaction below:CH₄ $\rightarrow$C₂H₂ + H₂What is the final pressure in a 100 L reaction vessel following the conversion of 323 g of methane to acetylene and hydrogen gases at 1725°C?

Accepted Answer

The balanced reaction is 2CH₄ → C₂H₂ + 3H₂. Calculate moles of CH₄: 323 g / 16.04 g/mol = 20.14 mol. From stoichiometry, 20.14 mol CH₄ produces 10.07 mol C₂H₂ and 30.21 mol H₂, totaling 40.28 mol of gas. Using the ideal gas law (PV=nRT), with R=0.08314 L·bar/mol·K and T=1998 K (1725°C + 273), P = (40.28 mol)(0.08314 L·bar/mol·K)(1998 K) / 100 L = 67.0 bar.

Question 4

The concentration of an old solution of hydrogen peroxide is being tested because hydrogen peroxide decomposes over time. The following reaction is catalyzed by potassium iodide and used to determine the concentration. If 3.0 ml of the peroxide solution is tested and produces 55 ml of O₂₍_g)at 750 mm Hg and 23°C, how many grams of hydrogen peroxide were in the solution? 2 H₂O₂₍_aq₎ $\rarr$ 2 H₂O_(l) + O_2(g)

Accepted Answer

Using the ideal gas law and stoichiometry, the moles of O2 produced can be calculated, which can then be used to find the moles and mass of H2O2 in the solution.

Question 5

Consider a sample of gas in a tank. Under which of the following conditions would you expect the most ideal behaviour?

Accepted Answer

Gases behave most ideally at high temperatures and low pressures because the particles have more kinetic energy and are less likely to interact with each other, minimizing intermolecular forces.

Question 6

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Accepted Answer

Under ideal conditions, all gases at the same temperature have the same average kinetic energy. The force exerted by a gas molecule or atom when it strikes the wall of a container is related to its kinetic energy, not its mass or size. Therefore, at the same temperature, all the listed molecules/atoms will exert the same force upon collision with the walls of the container.

Question 7

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Accepted Answer

Under ideal conditions, all gases at the same temperature have the same average kinetic energy. The force exerted when a molecule or atom strikes the wall of a container depends on its momentum change upon collision. Since all options have different temperatures, we compare based on the kinetic energy and mass. Helium atoms at 1500 K will have more kinetic energy due to the higher temperature, and being lighter, they will have higher velocities, leading to a greater force upon collision compared to the other options.

Question 8

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Accepted Answer

The force exerted by a molecule or atom when it strikes the wall of a container under ideal conditions is related to its momentum (mass times velocity). Although helium atoms have a much lower mass compared to the other options, their high velocity (800 m/s) compensates for this, resulting in a greater force upon impact due to the higher momentum change upon collision with the container walls.

Question 9

Increasing the number of molecules in a container increases the pressure because

Accepted Answer

The pressure inside a container increases with the number of molecules primarily because there are more collisions with the walls of the container. According to the kinetic theory of gases, the pressure exerted by a gas results from the force of gas molecules colliding with the walls of the container. Increasing the number of molecules increases the frequency of these collisions, thereby increasing the pressure, assuming the volume of the container and the temperature remain constant.

Question 10

Cooling the gas in a container lowers the pressure because

Accepted Answer

Cooling the gas reduces the kinetic energy of the molecules, causing them to move slower, which decreases both the force and frequency of their collisions with the container walls, thus lowering the pressure.

Question 11

Data for a pulsed molecular beam experiment at a temperature of 297 K is shown below:  Which are the following are probably true about the sample?1. The sample consists of two different molar mass molecules.2. The sample has a lower molar mass than ammonia (avg is 490 m/s).3. The sample has a higher molar mass than ammonia (avg is 490 m/s).4. The sample consists of molecules with the same molar mass.5. The average velocity is near 200 m/s.

Accepted Answer

The answer of Data for a pulsed molecular beam experiment...

Question 12

A sample of gas is heated from 200 K to 400 K. Which of the following statements accurately describes the sample at its new conditions?
1) The average velocity is twice as fast.
2) The molecules have four times the kinetic energy.
3) The average velocity is nearly the same.
4) The average kinetic energy is half the original.
5) The kinetic energy is twice the original.

Accepted Answer

The kinetic energy of a gas is directly proportional to its temperature in Kelvin. When the temperature doubles from 200 K to 400 K, the kinetic energy also doubles, making option 5 correct. The average velocity does increase, but not exactly twice as fast, and the kinetic energy certainly doesn't quadruple or halve, making the other statements incorrect.

Question 13

A sample of gas is cooled from 273°C to 0°C. Which of the following statements accurately describes the sample at its new conditions?
1) The kinetic energy is now nearly zero.
2) The average velocity is now twice as fast.
3) The average velocity is half as fast.
4) The average kinetic energy is halved.
5) The average velocity is about two thirds of the original.

Accepted Answer

The average kinetic energy of a gas is directly proportional to its absolute temperature (in Kelvin). When the gas is cooled from 273°C (546 K) to 0°C (273 K), its temperature is halved, which means its average kinetic energy is also halved (4). Since kinetic energy is related to the square of the velocity, a reduction in kinetic energy does not directly halve the velocity, but it does significantly reduce it, making (5) a reasonable approximation given the nature of kinetic energy and velocity relationship.

Question 14

A sample of gas is cooled to its vapourization temperature. What is true before the sample reaches equilibrium between the liquid and gaseous phases?

Accepted Answer

When a gas is cooled to its vaporization temperature and before equilibrium is reached, more molecules are condensing than vaporizing. This is because the system is transitioning from a gaseous state to a liquid state, leading to a net increase in the number of liquid molecules as they lose energy and condense.

Question 15

At 1000°C and 10.0 Torr, the density of a certain element in the gas phase is 2.9 x 10^-3 g/L. What is the element?

Accepted Answer

The answer of At 1000°C and 10.0 Torr, the density...

Question 16

A sample of N₂ gas is contaminated with a gas. It is found that that contaminant effuses at 0.36 times the rate of N₂. What is the contaminating gas?

Accepted Answer

The answer of A sample of N₂ gas is contaminated...

Question 17

A sample of radon is expected to diffuse ______ than oxygen gas.

Accepted Answer

Radon is heavier than oxygen, so according to Graham's law of effusion, the rate of diffusion of a gas is inversely proportional to the square root of its molar mass. Therefore, radon will diffuse slower than oxygen.

Question 18

A sample of oxygen is expected to diffuse ______ than chlorine gas.

Accepted Answer

Graham's law of effusion states that the rate of effusion of a gas is inversely proportional to the square root of its molar mass. Since oxygen (O2, molar mass ≈ 32 g/mol) is lighter than chlorine (Cl2, molar mass ≈ 71 g/mol), it will diffuse faster. The square root of the ratio of their molar masses (sqrt(71/32)) is approximately 1.5, meaning oxygen will diffuse 1.5 times faster than chlorine.

Question 19

The ideal gas equation is expected to be valid at

Accepted Answer

The ideal gas equation is expected to be valid at low pressure because at low pressures, the volume of the gas molecules themselves becomes negligible compared to the volume of the container, and the interactions between gas molecules are minimal, both assumptions of the ideal gas law.

Question 20

Consider the van der Waals "a" coefficient for He, O₂ andC₆H₆ increases because

Accepted Answer

The van der Waals "a" coefficient is a measure of the strength of the intermolecular forces acting between molecules. As these forces increase, the value of "a" increases, indicating stronger attractions between the particles.

Quiz 2: The Behaviour of Gases

The noxious gas H₂S can be used to remove the acid rain component SO₂ from factory emissions by the Claus Process. What volume of H₂Sin litres at STP will be needed to remove 2.00 kg of SO₂? 2 H₂S₍_g) + SO_2(g) $\rarr$ 3 S_(s) + 2 H₂O_(l)

Consider the conversion of methane to acetylene and hydrogen gas shown in the unbalanced reaction below:CH₄ $\rightarrow$ C₂H₂ + H₂What is the final pressure in a 100 L reaction vessel following the conversion of 323 g of methane to acetylene and hydrogen gases at 1725°C?

Consider a sample of gas in a tank. Under which of the following conditions would you expect the most ideal behaviour?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Increasing the number of molecules in a container increases the pressure because

Cooling the gas in a container lowers the pressure because

A sample of gas is cooled to its vapourization temperature. What is true before the sample reaches equilibrium between the liquid and gaseous phases?

At 1000°C and 10.0 Torr, the density of a certain element in the gas phase is 2.9 x 10^-3 g/L. What is the element?

A sample of N₂ gas is contaminated with a gas. It is found that that contaminant effuses at 0.36 times the rate of N₂. What is the contaminating gas?

A sample of radon is expected to diffuse ______ than oxygen gas.

A sample of oxygen is expected to diffuse ______ than chlorine gas.

The ideal gas equation is expected to be valid at

Consider the van der Waals "a" coefficient for He, O₂ andC₆H₆ increases because

Quiz 2: The Behaviour of Gases

The noxious gas H2S can be used to remove the acid rain component SO2 from factory emissions by the Claus Process. What volume of H2S in litres at STP will be needed to remove 2.00 kg of SO2? 2 H2S(g) + SO2(g) →\rarr→ 3 S(s) + 2 H2O(l)

Consider the conversion of methane to acetylene and hydrogen gas shown in the unbalanced reaction below:CH4 →\rightarrow→ C2H2 + H2What is the final pressure in a 100 L reaction vessel following the conversion of 323 g of methane to acetylene and hydrogen gases at 1725°C?

Consider a sample of gas in a tank. Under which of the following conditions would you expect the most ideal behaviour?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Which of the following molecules/atoms will exert a greater force when it strikes the wall of the container under ideal conditions?

Increasing the number of molecules in a container increases the pressure because

Cooling the gas in a container lowers the pressure because

A sample of gas is cooled to its vapourization temperature. What is true before the sample reaches equilibrium between the liquid and gaseous phases?

At 1000°C and 10.0 Torr, the density of a certain element in the gas phase is 2.9 x 10-3 g/L. What is the element?

A sample of N2 gas is contaminated with a gas. It is found that that contaminant effuses at 0.36 times the rate of N2. What is the contaminating gas?

A sample of radon is expected to diffuse ______ than oxygen gas.

A sample of oxygen is expected to diffuse ______ than chlorine gas.

The ideal gas equation is expected to be valid at

Consider the van der Waals "a" coefficient for He, O2 and C6H6 increases because

The noxious gas H₂S can be used to remove the acid rain component SO₂ from factory emissions by the Claus Process. What volume of H₂Sin litres at STP will be needed to remove 2.00 kg of SO₂? 2 H₂S₍_g) + SO_2(g) $\rarr$ 3 S_(s) + 2 H₂O_(l)

Consider the conversion of methane to acetylene and hydrogen gas shown in the unbalanced reaction below:CH₄ $\rightarrow$ C₂H₂ + H₂What is the final pressure in a 100 L reaction vessel following the conversion of 323 g of methane to acetylene and hydrogen gases at 1725°C?

At 1000°C and 10.0 Torr, the density of a certain element in the gas phase is 2.9 x 10^-3 g/L. What is the element?

A sample of N₂ gas is contaminated with a gas. It is found that that contaminant effuses at 0.36 times the rate of N₂. What is the contaminating gas?

Consider the van der Waals "a" coefficient for He, O₂ andC₆H₆ increases because