Y11 AQA REVISION 5 – Energy Changes

What is the principle of energy conservation in chemical reactions?

• The amount of energy in the universe decreases over time.

• The amount of energy in the universe increases during reactions.

• The amount of energy in the universe at the beginning is the same as at the end.

• The amount of energy in the universe is not related to chemical reactions.

Which describes an exothermic reaction?

• The reaction absorbs energy from the surroundings, decreasing the temperature.

• The reaction transfers energy to the surroundings, increasing the temperature.

• The product molecules have more energy than the reactants.

• The reaction occurs without any transfer of energy.

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

• Thermal decomposition

• The reaction of citric acid and sodium hydrogencarbonate

• Combustion

• A sports injury pack reaction

Which describes endothermic reactions?

• They release energy, increasing the temperature of the surroundings.

• They take in energy, increasing the temperature of the surroundings.

• They take in energy, decreasing the temperature of the surroundings.

• They occur spontaneously without energy change.

What is activation energy in the context of chemical reactions?

• The maximum amount of energy that particles must have to react.

• The minimum amount of energy that particles must have to react.

• The energy released when particles collide.

• The energy absorbed when a reaction is complete.

What can reaction profiles be used to show in a chemical reaction?

• The color change of the reaction

• The relative energies of reactants and products, and the overall energy change of a reaction

• The speed of the reaction

• The temperature at which the reaction occurs

How can you tell if a reaction is exothermic or endothermic?

• By measuring the duration of the reaction

• By checking the pH change of the reaction

• By looking at whether the reactants or products have more energy

• By observing the change in color of the reactants

What happens to energy during an exothermic reaction?

• Energy is taken in from the surroundings

• Energy is neither released nor absorbed

• Energy is released to the surroundings

• Energy is used to break bonds only

During a chemical reaction, when is energy supplied?

• When bonds in the reactants are formed

• When the reaction reaches equilibrium

• When bonds in the reactants are broken

• When the reaction is complete

What is the OVERALL ENERGY CHANGE in an ENDOTHERMIC reaction?

• Energy taken in to break bonds is LESS than energy released when bonds are formed

• Energy taken in to break bonds is EQUALto energy released when bonds are formed

• Energy taken in to break bonds is GREATER than energy released when bonds are formed

• NO energy change occurs