Chemical energy

Chemical reactions involve energy changes. Breaking bonds requires energy input, while forming new bonds releases energy. If the bond energy of the products is greater than that of the reactants, the reaction is exothermic, releasing energy as heat.

What is required to break chemical bonds?

• An input of energy

• A release of energy

• No energy is required

• A catalyst

What happens during the formation of new bonds?

• Energy is absorbed

• Energy is released

• No energy change

• Energy is transformed

What is the relationship between bond energy in products and reactants in an exothermic reaction?

• Products have lower bond energy

• Products have higher bond energy

• Bond energy is the same

• Reactants have higher bond energy

How can you determine if a reaction is exothermic?

• By comparing bond energies

• By measuring temperature

• By observing color change

• By the presence of a catalyst

Explain what happens to energy during an exothermic reaction.

• Energy is absorbed

• Energy is released as heat

• Energy remains constant

• Energy is converted to mass