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AP Chemistry Practice Quiz: Endothermic and Exothermic Processes

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 11 questions to check your progress.

Question 1 of 11

In an exothermic chemical reaction, which of the following best describes the change in the system's energy?

All Questions (11)

In an exothermic chemical reaction, which of the following best describes the change in the system's energy?

A) The system's energy decreases as energy is lost to the surroundings.

B) The system's energy increases as energy is gained from the surroundings.

C) The system's energy remains constant, but the surroundings' energy decreases.

D) The system's energy decreases as energy is gained from the surroundings.

Correct Answer: A

The provided content states that in an exothermic process, the system's energy decreases and this energy is lost to the surroundings.

A chemical process is classified as endothermic. Based on this classification, what is the expected experimental observation regarding the temperature of the immediate surroundings?

A) The temperature of the surroundings will increase.

B) The temperature of the surroundings will decrease.

C) The temperature of the surroundings will remain unchanged.

D) The temperature of the system will decrease, but the surroundings will not be affected.

Correct Answer: B

An endothermic process involves the system gaining energy from the surroundings. As the surroundings lose energy to the system, the temperature of the surroundings decreases.

A student mixes two chemicals in a test tube and observes that the test tube becomes noticeably colder to the touch. This observation indicates that the chemical transformation is which of the following?

A) Exothermic, because energy is being released as cold.

B) Endothermic, because the system is absorbing energy from the surroundings.

C) Exothermic, because the temperature of the system is decreasing.

D) Neither endothermic nor exothermic, as temperature change is a physical property.

Correct Answer: B

The content links experimental observations to energy changes. The test tube (surroundings) feeling colder means it has lost heat to the chemical reaction (the system). A process where the system gains energy from the surroundings is defined as endothermic.

Which of the following physical transformations is an example of an endothermic process?

A) Water vapor condensing on a cold window.

B) Liquid water freezing into ice.

C) Solid ice melting into liquid water.

D) A lit candle burning.

Correct Answer: C

The content identifies phase changes as examples of endothermic or exothermic processes. Melting requires the input of energy to break intermolecular bonds, meaning the system (the ice) absorbs energy from the surroundings. This is an endothermic process. Condensing and freezing release energy.

When a certain ionic compound is dissolved in water, the temperature of the resulting solution increases. Which statement best explains this observation?

A) The dissolution process is endothermic, causing the system's energy to increase.

B) The dissolution process is exothermic, as the system loses energy to the water.

C) The dissolution process is endothermic, as energy is absorbed from the ionic compound.

D) The dissolution process is exothermic, as the system gains energy from the water.

Correct Answer: B

The content states that solution formation can be exothermic or endothermic. An increase in the temperature of the solution (the surroundings) indicates that the dissolution process (the system) released energy. A process where the system loses energy to the surroundings is exothermic.

For a chemical reaction occurring in a beaker that is defined as the system, which statement is always true for an endothermic process?

A) The beaker feels hot, and the energy of the system increases.

B) The beaker feels cold, and the energy of the system decreases.

C) The beaker feels hot, and the energy of the system decreases.

D) The beaker feels cold, and the energy of the system increases.

Correct Answer: D

In an endothermic process, the system's energy increases because it gains energy from the surroundings. This transfer of energy from the surroundings (the beaker) to the system (the reaction) causes the temperature of the surroundings to drop, making the beaker feel cold.

What is the most direct experimental evidence that an energy change has occurred during a chemical or physical transformation in a solution?

A) A change in the color of the solution.

B) The formation of a gas.

C) A change in the temperature of the solution.

D) The precipitation of a solid.

Correct Answer: C

The provided content explicitly states that 'Temperature changes in a system indicate energy changes.' While other observations can occur, a change in temperature is the most direct measurement of heat being absorbed or released.

The formation of a solution depends on the relative strengths of intermolecular interactions. If the energy released from the formation of new solute-solvent interactions is greater than the energy required to break existing solute-solute and solvent-solvent interactions, the process is:

A) Exothermic, because there is a net release of energy.

B) Endothermic, because energy was required to break bonds.

C) Exothermic, because the overall energy of the system increases.

D) Endothermic, because the temperature of the surroundings will decrease.

Correct Answer: A

According to the content, the nature of the dissolution process depends on the relative strengths of interactions. If more energy is released (forming new interactions) than is absorbed (breaking old interactions), there is a net release of energy from the system to the surroundings, which defines an exothermic process.

A student observes the temperature of a substance increasing as it is heated on a hot plate. How can this process be described in terms of energy change?

A) Exothermic, because the substance is releasing heat.

B) Endothermic, because the substance is absorbing energy from the hot plate.

C) Exothermic, because the temperature of the system is increasing.

D) Neither, because no chemical transformation or phase change is occurring.

Correct Answer: B

The content lists the 'heating or cooling of a substance' as an example of an endothermic or exothermic process. In this case, the substance (the system) is gaining energy from the hot plate (the surroundings), causing its temperature to rise. This is an endothermic process.

During an exothermic process, energy is lost from the system to the surroundings. How can this energy transfer be manifested?

A) Only as a decrease in the system's temperature.

B) Only as an increase in the surroundings' temperature.

C) As heat or work transferred to the surroundings.

D) As work done on the system by the surroundings.

Correct Answer: C

The content specifies that for an exothermic process, 'energy is lost to the surroundings (as heat or work)'. This indicates that the energy transfer is not limited to just heat but can also include work done by the system on the surroundings.

A cold pack works because the dissolution of a salt inside, such as ammonium nitrate, absorbs heat from the environment. Which of the following correctly describes this process?

A) The dissolution is exothermic, and the system's energy decreases.

B) The dissolution is endothermic, and the system's energy increases.

C) The dissolution is exothermic, and the system's energy increases.

D) The dissolution is endothermic, and the system's energy decreases.

Correct Answer: B

The process absorbs heat from the environment (surroundings), which is the definition of an endothermic process. In an endothermic process, the system gains the energy that is lost by the surroundings, so the system's energy increases.