Chapter 7.3 Energy Changes in Reactions

What is an Endothermic Reaction?

A Reaction in which energy is absorbed.

What is an Exothermic Reaction?

A Reaction in which energy is released.

Is the phase change Vaporization Endo or Exothermic?

Endo, because the particles require energy to become a gas.

What is chemical energy?

Energy stored in chemical bonds

Is the phase change Condensation Endo or Exothermic?

Exo, because the particles have to release energy to become a liquid.

T/F: In an EXOthermic Reaction, the chemical energy of the reactants is less than that of the products.

False, in Exothermic reactions the energy of the reactants is released into the surroundings and therefore not present in the product of the reaction.

Does forming chemical bonds require or release energy?

Release

Does breaking chemical bonds require energy or release energy

Require

How does the reaction of propane and oxygen form energy?

The Oxygen atoms quickly form bonds with the propane forming energy.

What happens to chemical bonds during a chemical reaction.

They are broken

T/F: Combustion reactions are always Exothermic.

True

T/F: In an ENDOthermic reaction the energy of the products and the energy absorbed is equal to the energy of the products.

True, this is true for all reactions, the total energy of the reactants and energy absorbed is equal to the energy of the products, in Exothermic reactions, the energy of the reactants is equal to the energy of the products and the energy released. This is because of the conservation of mass.