Understanding Energy in Reactions

What is the main difference between exothermic and endothermic reactions?

• Exothermic reactions absorb energy, endothermic reactions release energy.

• Exothermic reactions release energy, endothermic reactions absorb energy.

• Both release energy.

• Both absorb energy.

Which of the following is a sign that a reaction is exothermic?

• The temperature of the surroundings decreases.

• The temperature of the surroundings increases.

• There is no temperature change.

• The reaction stops immediately.

• Exothermic

• Endothermic

• Neutral

• Catalytic

In an energy diagram, what does it mean if the products are at a lower energy level than the reactants?

• The reaction is endothermic.

• The reaction is exothermic.

• No energy is transferred.

• The reaction is incomplete.

Which of the following best describes an endothermic reaction?

• Energy is released to the surroundings.

• Energy is absorbed from the surroundings.

• No energy is transferred.

• Energy is created.

A student mixes two chemicals and notices the beaker feels cold. What type of reaction has likely occurred?

• Exothermic

• Endothermic

• Combustion

• Neutralisation

Which of the following reactions is most likely to be exothermic?

• Melting ice

• Burning wood

• Photosynthesis

• Evaporation of water

On an energy diagram, what does the vertical axis usually represent?

• Time

• Temperature

• Energy

• Mass

• Exothermic

• Endothermic

• Neutral

• Spontaneous

Which of the following statements is true for exothermic reactions?

• The products have more energy than the reactants.

• The reactants have more energy than the products.

• There is no energy change.

• Energy is only transferred as light.