Question 1

Which of the following best describes an endothermic reaction?

Accepted Answer

A reaction that absorbs heat from the surroundings, making the system feel cold to the touch.

Question 2

During an exothermic reaction, which of the following statements is true?

Accepted Answer

The system releases thermal energy to the surroundings.

Question 3

Which process is an example of an endothermic reaction?

Accepted Answer

Water boiling

Question 4

In an endothermic reaction, what happens to the bonds in the reactants?

Accepted Answer

Bonds are broken, requiring energy input.

Question 5

Which of the following energy diagrams best represents an exothermic reaction?

Accepted Answer

The products have lower energy than the reactants.

Question 6

A chemical cold pack used in sports injuries becomes cold when activated. What type of reaction is occurring inside the pack?

Accepted Answer

Endothermic, because it absorbs heat from the surroundings.

Question 7

Which of the following is a correct statement about exothermic reactions?

Accepted Answer

They release energy as bonds are formed in the products.

Question 8

If a reaction causes the temperature of the surroundings to increase, what can you infer about the reaction?

Accepted Answer

It is exothermic because it releases heat.

Question 9

Which of the following best explains why water boiling is an endothermic process?

Accepted Answer

Energy is absorbed to break the intermolecular forces between water molecules.

Question 10

A student mixes two chemicals in a beaker and observes that the beaker becomes warm. Which of the following best describes the energy change?

Accepted Answer

The reaction is exothermic, and energy is released to the surroundings.

Question 11

Which of the following phase changes is exothermic?

Accepted Answer

Steam condensing to liquid water

Question 12

In an exothermic reaction, which of the following is true about the energy of the products compared to the reactants?

Accepted Answer

The products have less energy than the reactants.

Question 13

Which of the following best describes the energy flow in an endothermic reaction?

Accepted Answer

Energy flows from the surroundings into the system.

Question 14

A reaction has the following energy diagram: the reactants start at a lower energy, and the products are at a higher energy. What type of reaction is this?

Accepted Answer

Endothermic

Question 15

Which of the following statements about bond energy is correct for exothermic reactions?

Accepted Answer

More energy is released when new bonds form in the products than is required to break the bonds in the reactants.

Endothermic and Exothermic Reactions: Key Concepts and Applications

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