Energy Transfer: Exothermic and Endothermic Changes Flashcards

Vocabulary flashcards reviewing key concepts, energy diagrams, phase changes, and dissolving processes for exothermic and endothermic changes based on lecture notes.

Mixture

A substance formed when two or more substances are combined without being chemically joined, allowing them to be easily separated.

Endothermic change

A process or reaction that takes in energy from the surroundings, causing the temperature of the surroundings to decrease.

Exothermic change

A process or reaction that transfers energy to the surroundings, causing the temperature of the surroundings to increase.

Exothermic reaction energy diagram

An energy level diagram showing reactants starting at a higher energy level and products ending at a lower energy level as energy is released.

Endothermic reaction energy diagram

An energy level diagram showing reactants starting at a lower energy level and products ending at a higher energy level as energy is absorbed.

Melting

An endothermic change of state where a substance absorbs energy to change from a solid to a liquid.

Evaporation / Boiling

An endothermic change of state where a substance absorbs energy to change from a liquid to a gas.

Sublimation

An endothermic change of state where particles absorb energy from the surroundings to change directly from a solid to a gas.

Freezing

An exothermic change of state where a substance releases energy to the surroundings to change from a liquid to a solid.

Condensation

An exothermic change of state where particles lose energy to the surroundings and move closer together, changing from a gas to a liquid as attractive forces increase.

Deposition

An exothermic change of state where a substance releases energy to change directly from a gas to a solid.

Dissolving Potassium chloride

An endothermic reaction in water that causes the temperature of the solution to drop from $20\,^{\circ}\text{C}$ to $12\,^{\circ}\text{C}$.

Dissolving Calcium chloride

An exothermic reaction in water that causes the temperature of the solution to rise from $20\,^{\circ}\text{C}$ to $39\,^{\circ}\text{C}$.

Dissolving Sodium hydrogen carbonate

An endothermic reaction in water that causes the temperature of the solution to drop from $20\,^{\circ}\text{C}$ to $16\,^{\circ}\text{C}$.

Dissolving Sodium carbonate

An exothermic reaction in water that causes the temperature of the solution to rise from $20\,^{\circ}\text{C}$ to $28\,^{\circ}\text{C}$.

Propanone evaporation

An endothermic process where liquid propanone absorbs energy from the fingers (surroundings), causing it to evaporate rapidly and feel cold.