(Acc)Chemical Reactions and Energy Concepts

What is activation energy?

• The energy released during a chemical reaction

• The minimum amount of energy needed to start breaking bonds in reactants

• The energy absorbed during an endothermic reaction

• The energy required to form new bonds

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

• Dissolving ammonium nitrate in water

• Burning wood

• Using a cold pack

• Melting ice

What happens in an endothermic reaction?

• Energy is released into the surroundings

• Energy is absorbed from the surroundings

• No energy change occurs

• Energy is released and absorbed equally

What is the role of activation energy in a chemical reaction?

• It determines the speed of the reaction

• It starts breaking bonds in reactants

• It forms new bonds in products

• It absorbs energy from surroundings

What happens to the surroundings during an exothermic reaction?

• They become colder

• They absorb energy

• They release energy

• They remain unchanged

What is a common example of an endothermic reaction?

• Burning wood

• Dissolving ammonium nitrate in water

• Combustion of fuel

• Freezing water

What does the size of activation energy affect?

• The amount of energy released

• The amount of energy absorbed

• How easily a reaction happens

• The type of reaction

What is the net change in energy called in a chemical reaction?

• Activation energy

• Reaction coordinate

• Enthalpy of reaction

• Energy balance

What is required for reactions with high activation energy to occur?

• A catalyst or heat

• More reactants

• Less energy

• A larger reaction coordinate

What does the reaction coordinate represent?

• The speed of the reaction

• The energy changes during a reaction

• The type of reaction

• The amount of activation energy