which of the following phase changes is (are) endothermic? 1 melting 2 vaporization 3 sublimation 4 condensation 5 deposition 6 freezing a. only 1 b. 1 and 2 2 and 3 a) 1, 2, and 3 only 2 f. 1 and 3 g. 1 and 4 h. 2, 3, and 4 i. 4, 5, and 6 j. 4 and 6 e. The diagram above illustrates the change in the vapor pressure of a liquid as the temperature is increased. Which arrow represents condensation? PRESSURE point a arrow ?. latn ‘arrow a point e point’o TEMPERATURE . If the atmospheric pressure over a sample of liquid is decreased, the boiling point of the liquid will a. always increase b. always decrease c. increase or decrease depending on the critical temperature of the liquid d. increase or decrease depending on the molecular weight of the liquid e. increase or decrease depending on the strength of the intermolecular bonding f. always remain constant
The Correct Answer and Explanation is :
Let’s go through each question and break them down for clarity:
Question 1: Which of the following phase changes is (are) endothermic?
Endothermic processes are those that absorb energy (usually in the form of heat) from the surroundings.
- Melting: Solid to liquid transition (absorbs heat).
- Vaporization: Liquid to gas transition (absorbs heat).
- Sublimation: Solid to gas transition (absorbs heat).
- Condensation: Gas to liquid transition (releases heat).
- Deposition: Gas to solid transition (releases heat).
- Freezing: Liquid to solid transition (releases heat).
The endothermic processes are those where energy is required to overcome intermolecular forces, which is the case for melting, vaporization, and sublimation.
Therefore, the correct answer is:
a) 1, 2, and 3 only.
Question 2: The diagram above illustrates the change in the vapor pressure of a liquid as the temperature is increased. Which arrow represents condensation?
Condensation is the process where a gas turns into a liquid. In the context of a phase diagram or vapor pressure graph, condensation occurs when the vapor pressure of the gas decreases as temperature decreases (which happens when you lower the temperature).
Since the diagram you’re referencing is not available to me directly, I can give you a general guideline:
- Condensation would be represented by an arrow pointing toward the liquid phase, where the vapor pressure curve starts to decrease as temperature is reduced.
Question 3: If the atmospheric pressure over a sample of liquid is decreased, the boiling point of the liquid will:
The boiling point is the temperature at which the vapor pressure of the liquid equals the external (atmospheric) pressure. As atmospheric pressure decreases, the liquid’s boiling point also decreases because the liquid doesn’t need to reach as high of a temperature to match the reduced pressure.
Thus, the correct answer is:
b) always decrease.
Summary:
- Endothermic phase changes: Melting, vaporization, sublimation (answer: a).
- Condensation occurs when the vapor pressure decreases (temperature lowers).
- Boiling point decrease when atmospheric pressure is lowered.
Feel free to ask if you need further clarification!