Question 1

A 1.43-g sample of an unknown pure gas occupies a volume of 0.333 L at a pressure of  and a temperature of 100.0°C.The unknown gas is

Accepted Answer

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Question 2

A 0.529-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

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Question 3

A gas mixture consists of N₂,SO₂,and Ar,where the mole fraction of N₂ is 0.55 and the mole fraction of Ar is 0.25.If the mixture is at STP in a 5.0 L container,how many molecules of SO₂ are present?

Accepted Answer

We can first find the mole fraction of SO₂ by subtracting the mole fractions of N₂ and Ar from 1: Mole fraction of SO₂ = 1 - 0.55 - 0.25 = 0.20 Next, we can use the ideal gas law to find the number of molecules of SO₂: PV = nRT where P = 1 atm, V = 5.0 L, n = number of moles, R = 0.0821 L•atm/mol•K (the gas constant), and T = 273 K (STP). Solving for n: n = PV/RT = (1 atm)(5.0 L)/(0.0821 L•atm/mol•K)(273 K) = 0.228 mol Now we can use Avogadro's number (6.022 × 10^23 molecules/mol) to convert from moles to molecules: Number of molecules of SO₂ = (0.20)(0.228 mol)(6.022 × 10^23 molecules/mol) = 2.74 × 10^22 molecules ≈ 2.7 × 10^22 molecules Therefore, the best choice is B.

Question 4

Which of the following samples has the greatest density at STP?

Accepted Answer

Density is mass per unit volume. At STP, all gases occupy the same volume (22.4 L for 1 mole), so the gas with the greatest molar mass will have the greatest density. SF₆ has the highest molar mass among the options given.

Question 5

Determine the density of N₂ gas at STP.

Accepted Answer

The formula N₂ decodes to N2S (Nitrogen disulfide). The molar mass of N2S is calculated as follows: Nitrogen (N) has an atomic mass of approximately 14 g/mol, and there are two nitrogen atoms, so 2 * 14 = 28 g/mol. Sulfur (S) has an atomic mass of approximately 32 g/mol, and there is one sulfur atom, so 1 * 32 = 32 g/mol. Adding these together gives a molar mass of 60 g/mol for N2S. At STP (standard temperature and pressure), 1 mole of any gas occupies 22.4 liters. Therefore, the density of N2S at STP can be calculated as the mass of 1 mole divided by the volume of 1 mole at STP: 60 g / 22.4 L = 2.68 g/L. However, since this option is not available and there seems to be a misunderstanding in the calculation or the interpretation of the formula, the correct approach to find the density of a gas at STP would typically involve using the molar mass and the volume occupied by 1 mole of gas at STP. Given the options and the potential for a typo or misinterpretation in the question or answer choices, the closest correct choice provided in the options based on standard calculations is not directly listed, indicating a need for clarification.

Question 6

What is the density of oxygen gas at STP?

Accepted Answer

At standard temperature and pressure (STP), the density of oxygen gas (O2) is 1.43 g/L. This can be calculated using the formula: density = (mass of substance) / (volume of substance). The molar mass of oxygen is 32 g/mol, so one mole of oxygen gas (O2) at STP occupies a volume of 22.4 L (as per Avogadro's Law). Therefore, the mass of one mole of oxygen gas at STP is 32 g, and the density of oxygen gas at STP is (32 g) / (22.4 L) = 1.43 g/L.

Question 7

The density of a gas is 1.43 g/L at STP.What is the gas?

Accepted Answer

The only gas with a density of 1.43 g/L at STP is O2 (oxygen). None of the other choices have a known density at STP that matches this value.

Question 8

Which of the following would have a density of 0.172 g/L at 7.0°C and 0.987 atm?

Accepted Answer

The density of a gas is directly proportional to its molar mass and inversely proportional to its temperature and pressure. Among the given options, only Helium (He) has a molar mass of 4 g/mol (close to the given density value of 0.172 g/L). Additionally, the temperature and pressure values are not significant factors in determining the correct answer.

Question 9

A mixture of F₂,H₂ and Xe have mole fractions of 0.25,0.65,and 0.10,respectively.What is the partial pressure of F₂ if the total pressure of the mixture is 3.9 atm?

Accepted Answer

The partial pressure of a gas in a mixture is given by the product of its mole fraction and the total pressure of the mixture. For F₂, with a mole fraction of 0.25 and a total pressure of 3.9 atm, the partial pressure is 0.25 * 3.9 atm = 0.975 atm, which rounds to 0.98 atm.

Question 10

A mixture of 0.220 moles Rn,0.350 moles O₂ and 0.640 moles Ar has a total pressure of 2.95 atm.What is the partial pressure of O₂?

Accepted Answer

To find the partial pressure of O₂, we need to use the mole fraction of O₂ in the mixture. First, we need to find the total moles of gas in the mixture: Total moles of gas = 0.220 moles Rn + 0.350 moles O₂ + 0.640 moles Ar = 1.21 moles Next, we can calculate the mole fraction of O₂: Mole fraction of O₂ = (0.350 moles O₂) / (1.21 moles) Mole fraction of O₂ = 0.289 Finally, we can use the mole fraction to calculate the partial pressure of O₂: Partial pressure of O₂ = Mole fraction of O₂ × Total pressure Partial pressure of O₂ = 0.289 × 2.95 atm Partial pressure of O₂ = 0.853 atm Therefore, the answer is B) 0.853 atm.

Question 11

In a container containing Ne,H₂,and CO₂,what is the mole fraction of Ne if the H₂ mole fraction is 0.22 and the CO₂ mole fraction is 0.58?

Accepted Answer

To find the mole fraction of Ne, we need to use the fact that the sum of mole fractions of all components in a mixture is equal to 1. 
Let x be the mole fraction of Ne, then we have:

x + 0.22 + 0.58 = 1

Simplifying this equation, we get:

x = 1 - 0.22 - 0.58 = 0.20

Therefore, the mole fraction of Ne is 0.20.

Question 12

A mixture of 0.220 moles CO,0.350 moles F₂ and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

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Question 13

A gas mixture contains Rn,He and N₂.What is the total pressure of the mixture,if the mole fraction of N₂ is 0.350 and the partial pressure of N₂ is 0.580 atm?

Accepted Answer

First, we need to determine the mole fractions of Rn and He in the mixture. We know that the mole fraction of N₂ is 0.350, so the mole fraction of the other two gases must add up to 1 - 0.350 = 0.650. Next, we can use the partial pressure of N₂ to find the total pressure of the mixture. We know that the partial pressure of N₂ is 0.580 atm. We can use the mole fraction of N₂ to find its contribution to the total pressure: P(N₂) = mole fraction of N₂ x total pressure 0.580 atm = 0.350 x total pressure Solving for the total pressure: total pressure = 0.580 atm / 0.350 total pressure = 1.657 atm Rounding to two decimal places, we get the answer of 1.66 atm, which is choice A.

Question 14

Give the gas that is the lowest percent by volume in dry gas.

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Question 15

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Accepted Answer

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Question 16

Place the following gases in order of increasing density at STP. N₂ NH₃ N₂O₄ Kr

Accepted Answer

Density at STP is proportional to molar mass. NH3 (17 g/mol) < N2 (28 g/mol) < Kr (84 g/mol) < N2O4 (92 g/mol).

Question 17

The density of nitric oxide (NO)gas at 1.35 atm and 29.8°C is ________ g/L.

Accepted Answer

The density of a gas can be calculated using the ideal gas law rearranged to find density: $ \text{density} = \frac{PM}{RT} $. Here, P = 1.35 atm, M (molar mass of NO) = 30.01 g/mol, R = 0.0821 L·atm/mol·K, and T = 29.8°C = 302.95 K. Plugging in these values gives a density of approximately 1.63 g/L.

Question 18

The density of krypton gas at 1.35 atm and 54.1°C is ________ g/L.

Accepted Answer

To find the density of krypton gas, use the ideal gas law rearranged to find density: $ \text{Density} = \frac{PM}{RT} $. Here, P = 1.35 atm, M (molar mass of Kr) = 83.8 g/mol, R = 0.0821 L·atm/mol·K, and T = 54.1°C = 327.25 K. Plugging in these values gives a density of approximately 4.21 g/L.

Question 19

A mixture of Ar,H₂ and SO₂ has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H₂ has a mole fraction of 0.23,what is the partial pressure of SO₂?

Accepted Answer

The mole fraction of $SO_2$ can be found by subtracting the mole fractions of Ar and $H_2$ from 1. This gives $1 - 0.47 - 0.23 = 0.30$. The partial pressure of $SO_2$ is then $0.30 \times 7.85 \, \text{atm} = 2.355 \, \text{atm}$, which rounds to 2.4 atm, making option E correct.

Question 20

The density of chlorine gas at 0.866 atm and 39.9°C is ________ g/L.

Accepted Answer

Using the ideal gas law, the density of chlorine gas can be calculated as: density = (P * M) / (R * T), where P = 0.866 atm, M = 70.9 g/mol (molar mass of Cl2), R = 0.0821 L·atm/mol·K, and T = 313.05 K (39.9°C in Kelvin). This gives a density of approximately 2.39 g/L.

Quiz 5: Gases

A 1.43-g sample of an unknown pure gas occupies a volume of 0.333 L at a pressure of and a temperature of 100.0°C.The unknown gas is

A 0.529-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

A gas mixture consists of N₂,SO₂,and Ar,where the mole fraction of N₂ is 0.55 and the mole fraction of Ar is 0.25.If the mixture is at STP in a 5.0 L container,how many molecules of SO₂ are present?

Which of the following samples has the greatest density at STP?

Determine the density of N₂ gas at STP.

What is the density of oxygen gas at STP?

The density of a gas is 1.43 g/L at STP.What is the gas?

Which of the following would have a density of 0.172 g/L at 7.0°C and 0.987 atm?

A mixture of F₂,H₂ and Xe have mole fractions of 0.25,0.65,and 0.10,respectively.What is the partial pressure of F₂ if the total pressure of the mixture is 3.9 atm?

A mixture of 0.220 moles Rn,0.350 moles O₂ and 0.640 moles Ar has a total pressure of 2.95 atm.What is the partial pressure of O₂?

In a container containing Ne,H₂,and CO₂,what is the mole fraction of Ne if the H₂ mole fraction is 0.22 and the CO₂ mole fraction is 0.58?

A mixture of 0.220 moles CO,0.350 moles F₂ and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

A gas mixture contains Rn,He and N₂.What is the total pressure of the mixture,if the mole fraction of N₂ is 0.350 and the partial pressure of N₂ is 0.580 atm?

Give the gas that is the lowest percent by volume in dry gas.

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Place the following gases in order of increasing density at STP. N₂ NH₃ N₂O₄ Kr

The density of nitric oxide (NO) gas at 1.35 atm and 29.8°C is ________ g/L.

The density of krypton gas at 1.35 atm and 54.1°C is ________ g/L.

A mixture of Ar,H₂ and SO₂ has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H₂ has a mole fraction of 0.23,what is the partial pressure of SO₂?

The density of chlorine gas at 0.866 atm and 39.9°C is ________ g/L.

Quiz 5: Gases

A 1.43-g sample of an unknown pure gas occupies a volume of 0.333 L at a pressure of and a temperature of 100.0°C.The unknown gas is

A 0.529-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

A gas mixture consists of N2,SO2,and Ar,where the mole fraction of N2 is 0.55 and the mole fraction of Ar is 0.25.If the mixture is at STP in a 5.0 L container,how many molecules of SO2 are present?

Which of the following samples has the greatest density at STP?

Determine the density of N2 gas at STP.

What is the density of oxygen gas at STP?

The density of a gas is 1.43 g/L at STP.What is the gas?

Which of the following would have a density of 0.172 g/L at 7.0°C and 0.987 atm?

A mixture of F2,H2 and Xe have mole fractions of 0.25,0.65,and 0.10,respectively.What is the partial pressure of F2 if the total pressure of the mixture is 3.9 atm?

A mixture of 0.220 moles Rn,0.350 moles O2 and 0.640 moles Ar has a total pressure of 2.95 atm.What is the partial pressure of O2?

In a container containing Ne,H2,and CO2,what is the mole fraction of Ne if the H2 mole fraction is 0.22 and the CO2 mole fraction is 0.58?

A mixture of 0.220 moles CO,0.350 moles F2 and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

A gas mixture contains Rn,He and N2.What is the total pressure of the mixture,if the mole fraction of N2 is 0.350 and the partial pressure of N2 is 0.580 atm?

Give the gas that is the lowest percent by volume in dry gas.

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Place the following gases in order of increasing density at STP. N2 NH3 N2O4 Kr

The density of nitric oxide (NO) gas at 1.35 atm and 29.8°C is ________ g/L.

The density of krypton gas at 1.35 atm and 54.1°C is ________ g/L.

A mixture of Ar,H2 and SO2 has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H2 has a mole fraction of 0.23,what is the partial pressure of SO2?

The density of chlorine gas at 0.866 atm and 39.9°C is ________ g/L.

A gas mixture consists of N₂,SO₂,and Ar,where the mole fraction of N₂ is 0.55 and the mole fraction of Ar is 0.25.If the mixture is at STP in a 5.0 L container,how many molecules of SO₂ are present?

Determine the density of N₂ gas at STP.

A mixture of F₂,H₂ and Xe have mole fractions of 0.25,0.65,and 0.10,respectively.What is the partial pressure of F₂ if the total pressure of the mixture is 3.9 atm?

A mixture of 0.220 moles Rn,0.350 moles O₂ and 0.640 moles Ar has a total pressure of 2.95 atm.What is the partial pressure of O₂?

In a container containing Ne,H₂,and CO₂,what is the mole fraction of Ne if the H₂ mole fraction is 0.22 and the CO₂ mole fraction is 0.58?

A mixture of 0.220 moles CO,0.350 moles F₂ and 0.640 moles He has a total pressure of 2.95 atm.What is the partial pressure of CO?

A gas mixture contains Rn,He and N₂.What is the total pressure of the mixture,if the mole fraction of N₂ is 0.350 and the partial pressure of N₂ is 0.580 atm?

Place the following gases in order of increasing density at STP. N₂ NH₃ N₂O₄ Kr

A mixture of Ar,H₂ and SO₂ has a pressure of 7.85 atm.If the Ar has a mole fraction of 0.47 and H₂ has a mole fraction of 0.23,what is the partial pressure of SO₂?