1.
Which gas law applies in conjunction with Dalton's law?
Correct Answer
A. Henry's law
Explanation
Henry's law applies in conjunction with Dalton's law. Dalton's 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. Henry's law, on the other hand, states that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid. Therefore, Henry's law is used to calculate the solubility of gases in liquids when considering the partial pressures of the gases according to Dalton's law.
2.
What is the mole fraction of oxygen in the mixture if the partial pressure of hydrogen is 1 atm? A mixture of hydrogen gas and oxygen gas exerts a total pressure of 1.5 atm on the walls of its container.
Correct Answer
C. 0.33
Explanation
The mole fraction of a gas in a mixture is the ratio of the number of moles of that gas to the total number of moles in the mixture. In this case, the partial pressure of hydrogen is given as 1 atm, which means that the mole fraction of hydrogen can be calculated as 1 atm divided by the total pressure of 1.5 atm, resulting in a mole fraction of 0.67. Since the mixture only contains hydrogen and oxygen, the mole fraction of oxygen can be calculated by subtracting the mole fraction of hydrogen from 1, resulting in a mole fraction of 0.33.
3.
What does Dalton's law of partial pressures state?
Correct Answer
A. The total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases.
Explanation
Dalton's law of partial pressures states that the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases. This means that each gas in a mixture exerts its own pressure independently of the other gases present. The total pressure is simply the sum of these individual pressures.
4.
Dalton's law is related to the ideal gas laws.
Correct Answer
A. True
Explanation
Dalton's law states that the total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressures of each individual gas. This law is a fundamental concept in the study of ideal gases. It helps explain the behavior of gas mixtures and is often used in various scientific and engineering applications. Therefore, the statement that Dalton's law is related to the ideal gas laws is true.
5.
Dalton's law equation is written as
Correct Answer
C. P_{total} = P_{1} + P_{2} + P_{3} + …. + P_{n}
Explanation
The correct answer is "Ptotal = P1 + P2 + P3 + ... + Pn" because Dalton's 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 in the mixture. This equation represents the summation of the partial pressures of all gases present in the mixture to determine the total pressure.
6.
Which expression represents the pressure exerted by a gas?
Correct Answer
C. P = nRT/V
Explanation
The expression P = nRT/V represents the pressure exerted by a gas. This equation is derived from the ideal gas law, where P represents pressure, n represents the number of moles of gas, R is the ideal gas constant, T is the temperature in Kelvin, and V is the volume of the gas. By rearranging the equation, we can solve for pressure, making P = nRT/V the correct expression for gas pressure.
7.
What is the partial pressure of oxygen (in kPa) if the total pressure is 200 kPa? An ideal gas mixture of oxygen (Molecular weight = 32 kg/kmol) and carbon dioxide (molecular weight = 44 kg/kmol) has a mass composition of 40% and 60%, respectively.
Correct Answer
C. 95.52 kPa
Explanation
The partial pressure of oxygen can be calculated using the formula:
Partial pressure of oxygen = Total pressure * (Mass fraction of oxygen * Molecular weight of oxygen) / (Sum of mass fractions * Molecular weight of the mixture)
In this case, the mass fraction of oxygen is 40% (or 0.4), the molecular weight of oxygen is 32 kg/kmol, and the molecular weight of the mixture is (0.4 * 32) + (0.6 * 44) = 36.8 kg/kmol.
Plugging these values into the formula, we get:
Partial pressure of oxygen = 200 kPa * (0.4 * 32) / 36.8 = 95.52 kPa
Therefore, the correct answer is 95.52 kPa.
8.
The salting-out effect of a given salt is almost dependent on the nature of the gas.
Correct Answer
B. False
Explanation
The salting-out effect of a given salt is not dependent on the nature of the gas. The salting-out effect refers to the ability of a salt to decrease the solubility of a nonpolar substance in a solvent. This effect is primarily determined by the properties of the salt and solvent, rather than the nature of the gas. Therefore, the statement is false.
9.
Under what circumstances Dalton's law is approximately valid for real gases?
Correct Answer
C. Both A and B
Explanation
Dalton's law states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of each individual gas. This law is approximately valid for real gases under low pressures and high temperatures. At low pressures, the intermolecular forces between gas molecules are weak, and the volume occupied by the gas molecules is negligible compared to the total volume. At high temperatures, the kinetic energy of the gas molecules is high enough to overcome intermolecular forces, allowing the gas molecules to behave more like ideal gases. Therefore, under these circumstances, Dalton's law is approximately valid for real gases.
10.
What is the partial pressure of water vapor if a mixture of hydrogen, nitrogen, and water vapor has a total pressure of 864 mmHg? Given: The partial pressure of hydrogen is 220 mmHg, and that of nitrogen is 410 mmHg.
Correct Answer
A. 234 mmHg
Explanation
The partial pressure of water vapor can be calculated by subtracting the partial pressures of hydrogen and nitrogen from the total pressure. Therefore, the partial pressure of water vapor is 864 mmHg - 220 mmHg - 410 mmHg = 234 mmHg.