Question 1

Which of the following best describes the difference between temperature and heat?

Accepted Answer

Temperature is a measure of the average kinetic energy of particles, while heat is the transfer of energy due to a temperature difference.

Question 2

During which phase change does the system absorb energy from the surroundings?

Accepted Answer

Melting

Question 3

Which of the following phase changes is classified as exothermic?

Accepted Answer

Freezing

Question 4

A student heats ice at $0\ ^\circ\mathrm{C}$ until it becomes steam at $100\ ^\circ\mathrm{C}$. Which phase changes occur during this process?

Accepted Answer

Melting and vaporization

Question 5

According to the first law of thermodynamics, which equation correctly relates the change in internal energy ($\Delta U$) of a system to heat ($q$) and work ($w$)?

Accepted Answer

$\Delta U = q + w$

Question 6

Which of the following is NOT one of the six common phase changes?

Accepted Answer

Combustion

Question 7

If $\Delta T$ is positive during a process, what does this indicate about the temperature of the system?

Accepted Answer

The temperature increased.

Question 8

Which of the following statements about chemical energy is correct?

Accepted Answer

Chemical energy is a form of potential energy.

Question 9

A sample of water at $100\ ^\circ\mathrm{C}$ undergoes condensation. What happens to the thermal energy of the system?

Accepted Answer

Thermal energy is released to the surroundings.

Question 10

Which of the following best describes an endothermic phase change?

Accepted Answer

Energy is absorbed from the surroundings.

Question 11

During the freezing of water, which of the following statements is true regarding the system and surroundings?

Accepted Answer

The system releases energy to the surroundings.

Question 12

Which phase change occurs when dry ice ($\mathrm{CO}_2$ (s)) turns directly into gas?

Accepted Answer

Sublimation

Question 13

A chemical cold pack becomes cold when activated. Which type of process is occurring?

Accepted Answer

Endothermic process

Question 14

Which of the following is an example of thermal energy?

Accepted Answer

Energy due to the motion of particles

Question 15

If a system does $50\ \mathrm{J}$ of work on the surroundings and absorbs $100\ \mathrm{J}$ of heat, what is the change in internal energy ($\Delta U$)?

Accepted Answer

$\Delta U = 50\ \mathrm{J}$

Question 16

Which symbol is commonly used to indicate a change in a property, such as temperature?

Accepted Answer

$\Delta$

Question 17

Which of the following best describes the surroundings in a chemical reaction occurring in a beaker?

Accepted Answer

The beaker and everything outside it

Question 18

Which phase change is involved when frost forms on a cold window during winter?

Accepted Answer

Deposition

Question 19

Which of the following statements is true regarding energy changes during phase transitions?

Accepted Answer

All phase changes are accompanied by energy changes.

Question 20

A student interprets a simple energy diagram for the vaporization of water. Which of the following is correct?

Accepted Answer

The diagram shows energy being absorbed from the surroundings.

Introduction to Energy and Phase Changes in General Chemistry

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