Chemical reactions and energy

Chemical reactions and energy

Chemical Reactions - Energy Exchanges

• All reactions release or absorb energy

• This energy can take many forms (heat, light, sound, etc.)

• energy is absorbed when bonds break

• energy is released when bonds form

More energy out

• Chemical reactions that release energy are called exergonic reactions

• The activation energy required to break the original bonds is less than the energy released when the new bonds form

Thermal energy release

• If the primary energy release is thermal energy, we call the reaction an exothermic reaction

• These reactions provide most of the power used in homes and industry

More Energy In

• Reactions that require more energy to break the original bonds than what is released when the new bonds form are called endergonic reactions

• Electricity is often used to provide the energy necessary for the reaction to occur

Thermal Energy Absorbed

• If the energy needed to keep a reaction going is in the form of thermal energy we call the reaction an endothermic reaction

Multiple Choice

Energy is ______ when bonds break.

• gained

• lost

• released

• absorbed

Multiple Choice

Energy is _____ when new bonds form.

• absorbed

• released

• lost

• gained

Multiple Choice

The energy required to start a chemical reaction is ___.

• endothermic

• exothermic

• activation

• released

Multiple Choice

An _______ reaction is when more thermal energy is absorbed than is released.

• endothermic

• endergonic

• exothermic

• exergonic

Multiple Choice

An _______ reaction is when more thermal energy is released than is absorbed.

• endothermic

• endergonic

• exothermic

• exergonic

Multiple Choice

In a _____ reaction, the reactants have more energy than the products.

• endergonic

• exergonic

Multiple Choice

An _______ reaction is when more energy is absorbed than is released. This energy can be in the form of light, heat, electricity, etc.

• endothermic

• endergonic

• exothermic

• exergonic

Multiple Choice

In a _____ reaction, the products have more energy than the reactants.

• exergonic

• endergonic

Multiple Choice

An _______ reaction is when more energy is released than is absorbed. This energy can be in the form of light, heat, electricity, etc.

• endothermic

• endergonic

• exothermic

• exergonic

Conservation Of Energy

• Remember that energy cannot be created or destroyed only transformed

• In chemical reactions the energy of the reactants has to be equal to the energy of the products plus any energy released