1.
The vapor pressure of a substance increases as temperature increases.
Correct Answer
A. True
Explanation
As temperature increases, the kinetic energy of the molecules in a substance also increases. This leads to an increase in the number of molecules with enough energy to escape from the liquid phase and enter the gas phase, resulting in an increase in vapor pressure. Therefore, it is true that the vapor pressure of a substance increases as temperature increases. Kinetic energy (EK)is directly proportional to Temperature(ΔT), and ΔT is directly proportional to vapor pressure (P). So, as ΔT increases, P will also increase.
2.
What factors affect vapor pressure?
Correct Answer
D. All of the above
Explanation
Vapor pressure is affected by several factors. The surface area of a liquid can affect vapor pressure because a larger surface area allows more molecules to escape into the gas phase, increasing the vapor pressure. The nature of the liquid also plays a role as different liquids have different intermolecular forces, which affect the ease with which molecules can escape into the gas phase. Lastly, temperature affects vapor pressure because as temperature increases, the kinetic energy of the molecules increases, leading to more molecules escaping into the gas phase and thus increasing the vapor pressure. Therefore, all of the factors mentioned (surface area, nature of liquid, and temperature) can affect vapor pressure.
3.
Which law describes the relationship between the pressure and temperature of a gas?
Correct Answer
A. Gay Lussac's Law
Explanation
Gay Lussac's Law describes the relationship between the pressure and temperature of a gas. According to this law, the pressure of a gas is directly proportional to its temperature, provided that the volume and amount of gas remain constant. This means that as the temperature of a gas increases, its pressure will also increase, and vice versa.
4.
What happens if the vapor is contained in a sealed vessel?
Correct Answer
D. All of the above
Explanation
If the vapor is contained in a sealed vessel, all of the given options are likely to occur. The vapor pressure will increase, reaching a point where it becomes too high. This can lead to the vessel exploding due to the build-up of pressure. Additionally, the matter will continue to evaporate and transition into the gas phase. Therefore, all of the above options are possible outcomes when vapor is contained in a sealed vessel.
5.
The vapor pressure of a liquid is dependent on the volume of liquid in the container.
Correct Answer
B. False
Explanation
The vapor pressure of a liquid is not dependent on the volume of liquid in the container. Vapor pressure is determined by the temperature and the nature of the liquid itself, not by the volume of the liquid. Increasing or decreasing the volume of the liquid in the container will not affect its vapor pressure.
6.
What factors affect evaporation?
Correct Answer
C. Both A and B
Explanation
The process of evaporation depends on both the nature of the liquid and the effect of temperature. The nature of the liquid refers to its physical properties, such as its surface tension and vapor pressure, which determine how easily it can evaporate. The effect of temperature is also important, as higher temperatures generally increase the rate of evaporation by providing more energy to the liquid molecules, causing them to escape into the air more rapidly. Therefore, both factors play a role in the process of evaporation.
7.
Raoult's law equation is expressed through this formula:
Correct Answer
B. Psolution = ΧsolventP0solvent.
Explanation
The correct answer is Psolution = ΧsolventP0solvent because Raoult's law states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent in the solution. Therefore, the equation Psolution = ΧsolventP0solvent represents Raoult's law accurately.
8.
Does vapor pressure increase with the increase in the boiling point?
Correct Answer
B. No
Explanation
Vapor pressure and boiling point are inversely related. As the boiling point increases, the vapor pressure decreases. This is because higher boiling points indicate stronger intermolecular forces, which require more energy to break and convert the liquid into a gas. Consequently, the vapor pressure decreases as more energy is needed to overcome these forces and reach the boiling point. Therefore, the correct answer is "No."
9.
Which of the following has extremely low vapor pressures?
Correct Answer
A. Triglycerides
Explanation
Triglycerides have extremely low vapor pressures. Triglycerides are a type of lipid molecule composed of three fatty acid chains attached to a glycerol backbone. Due to their large size and nonpolar nature, triglycerides have weak intermolecular forces and do not easily evaporate into a gas phase. This results in their low vapor pressure compared to other substances, such as carbohydrates, which are more likely to evaporate and have higher vapor pressures.
10.
When two immiscible liquids are in a mixture, what happens to their boiling points?
Correct Answer
B. It decreases.
Explanation
When two immiscible liquids are in a mixture, their boiling points decrease. This is because the presence of another liquid lowers the vapor pressure of each individual liquid, making it easier for them to evaporate and reach their boiling points. Therefore, the boiling points of the immiscible liquids in the mixture are lower compared to their boiling points when they are pure.