GCSE 2.8 Energy Changes in Chemistry

Which of the following statements is true about exothermic reactions?

• Exothermic reactions absorb heat from the surroundings.

• Exothermic reactions release heat to the surroundings.

• Exothermic reactions have a positive ΔH (energy change).

• Exothermic reactions decrease the temperature of the surroundings.

What is the minimum energy needed for a reaction to occur called?

• Bond energy

• Activation energy

• Reaction energy

• Thermal energy

In an exothermic reaction, what happens to the temperature of the surroundings?

• It decreases.

• It remains the same.

• It increases.

• It fluctuates.

Which of the following is an example of an exothermic reaction?

• Photosynthesis

• Melting of ice

• Combustion of methane

• Evaporation of water

What happens to energy during bond breaking and bond making in a chemical reaction?

• Bond breaking releases energy and bond making takes in energy.

• Bond breaking takes in energy and bond making releases energy.

• Both bond breaking and bond making release energy.

• Both bond breaking and bond making take in energy.

Which of the following chemical equations represents the combustion of methane?

• CH₄ + 2O₂ → CO₂ + 2H₂O

• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

• 2H₂ + O₂ → 2H₂O

• N₂ + 3H₂ → 2NH₃

Which of the following is a product of respiration in living things?

• CH₄

• O₂

• CO₂

• H₂O

Which of the following statements is true about exothermic reactions?

• The energy change is positive.

• The energy change is negative.

• The products have higher energy than the reactants.

• The surroundings feel cooler.

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

• Combustion of methane

• Freezing of water

• Thermal decomposition of calcium carbonate

• Condensation of steam

In endothermic reactions, what happens to the temperature of the surroundings?

• It increases.

• It decreases.

• It remains the same.

• It fluctuates.