Physical and Chemical Changes, Exothermic and Endothermic Reactions

These flashcards cover key concepts related to physical and chemical changes, as well as exothermic and endothermic reactions, including definitions, examples, and processes.

What is a physical change?

A change in the physical state or appearance of a substance without altering its chemical composition.

What is a chemical change?

A change that occurs when a new substance is formed due to a chemical reaction.

What are two examples of physical changes?

Melting ice and dissolving sugar in water.

What defines an exothermic reaction?

A chemical reaction that releases energy to the surroundings, usually as heat or light.

What happens to the temperature of the surroundings during an exothermic reaction?

The temperature of the surroundings increases.

Give an example of an endothermic reaction.

Photosynthesis is an example of an endothermic reaction.

What is bond breaking?

The process that requires energy input and is always an endothermic process.

What is bond making?

The process that releases energy and is always an exothermic process.

What is activation energy (Ea)?

The minimum energy required to start a chemical reaction.

How is enthalpy change (ΔH) measured?

It is measured in kilojoules per mole (kJ/mol) and can be negative for exothermic reactions or positive for endothermic reactions.