Endothermic and Exothermic Reactions

System

materials involved in the chemical reaction

Surrounding

everyrhing else in the universe

Open-System

both matter and energy can freely cross from the system to the surrounding and back again

Closed-System

energy can cross the boundary but matter cannot

Isolated -System

neither matter nor energy can cross between the system and the surroundings

Physical Change

molecules may be rearranged but no new substance is produced (eg. cutting, texture, shape, dissolving in water, changes in state)

Chemical Change

A change in matter that produces one or more new substances (eg. gas is produced, light is given off, change in temp, etc)

Endothermic reaction

When more energy is absorbed by the system than is released into the surroundings (eg. melting ice, photosynthesis)

Exothermic Reaction

When more energy is released into the surrounding than is absorbed by the system (eg. combustion, solidification, bond making)

Rate or Reaction

The speed of reaction