1) Liquid oxygen undergoes an endothermic phase change. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) q is positive.
(b) Energy is transferred from the system to the surroundings.
(c) ΔH is positive.
(d) The surroundings do work on the system.
2) Liquid chlorine undergoes a phase change having a positive ΔH. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) The chlorine evaporated into a gas.
(b) Energy was transferred from the system to the surroundings.
(c) It was an exothermic reaction.
(d) Energy was transferred from the surroundings to the system.
3) Carbon dioxide undergoes a phase change that takes energy from the surroundings. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) The surroundings did work on the system.
(b) It was an endothermic reaction.
(c) ΔH is negative.
(d) q is positive.
4) A liquid freezes into a solid. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) The system did work on the surroundings.
(b) ΔH is positive.
(c) It was an exothermic reaction.
(d) q is negative.
5) A gas condenses into a liquid. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) ΔH is negative.
(b) Energy was transferred from the surroundings to the system.
(c) q is positive.
(d) It was an exothermic reaction.
6) Liquid iodine undergoes a phase change that has a negative q value. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) Energy was transferred from the system to the surroundings.
(b) It was an endothermic reaction.
(c) The liquid became a solid.
(d) ΔH is negative.
7) Liquid nitrogen evaporates to a gas. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) The system does work on the surroundings.
(b) q is negative.
(c) ΔH is positive.
(d) This is an exothermic reaction.
8) A phase change of liquid iodine has a negative ΔH value. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) Iodine became a gas.
(b) Energy was transferred from the system to the surroundings.
(c) It was an exothermic reaction.
(d) q is positive.
9) Liquid bromine undergoes an exothermic phase change. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) ΔH is negative.
(b) Bromine solidified.
(c) q is positive.
(d) The system did work on the surroundings.
10) A solid melts to a liquid. Assuming a constant pressure and a flexible container, which of the following statements are true?
(a) This is an endothermic reaction.
(b) q is positive.
(c) The surroundings do work on the system.
(d) ΔH is negative.