Energy Changes in Reactions

These flashcards cover key concepts related to energy changes in chemical reactions, including definitions of terms and examples.

Reactants

The starting substances in a chemical reaction.

Products

The substances made in a chemical reaction.

Exothermic Reaction

An energy transfer that releases energy to the surroundings.

Endothermic Reaction

An energy transfer that absorbs energy from the surroundings.

Bond Energy

The energy required to break a bond or the energy released when a bond is formed.

Activation Energy

The minimum amount of energy required for a collision to result in a reaction.

Thermal Decomposition

An endothermic reaction where a compound breaks down into simpler substances.

Combustion

An exothermic reaction involving the burning of a substance.

Neutralisation Reaction

An exothermic reaction where an acid and a base react to form water and a salt.

Bond Breaking

An endothermic process that requires energy to break chemical bonds.

Bond Formation

An exothermic process that releases energy when new bonds are formed.

Exothermic Reaction (in terms of bonds)

Less energy is required to break the bonds than is released when making the bonds.

Endothermic Reaction (in terms of bonds)

More energy is required to break the bonds than is released when making the bonds.

Negative Energy Change

Indicates an exothermic reaction.

Positive Energy Change

Indicates an endothermic reaction.

Chemical Cell

A device that produces electricity through a chemical reaction.

Battery

Two or more chemical cells connected in series.

Fuel Cell

A cell that uses fuel and oxygen to generate electricity.

Hydrogen Fuel Cell Reaction

2H2 (g) + O2 (g) ➞ 2H2O (l).

Advantage of Hydrogen Fuel Cell

Only product is water, does not need to be electrically recharged.

Disadvantage of Hydrogen Fuel Cell

Hydrogen is flammable, difficult to store, and often produced from non-renewable sources.