whenever chemical reactions occur, energy is transferred to or from the surroundings. an exothermic...

Whenever chemical reactions occur, energy is transferred to or from the surroundings.

An exothermic reaction is one which transfers heat energy to the surroundings

An endothermic reaction is one which takes heat energy from the surroundings

Exothermic process: a physical or chemical change that releases heat energy

Burning fossil fuels is an exothermic reaction.

reaction

Exothermic Change - heat Exothermic Change - heat is given off and the is given off and the temperature risestemperature rises

Reactants Products

A + B AB

Forming a Chemical Bond - Releases Energy

EXOTHERMIC EXAMPLES

A candle flame

Rusting iron

Burning sugar

Glow sticks

Fire crackers

Some hand warmers

Burning Wood

Freezing Water

Endothermic process: a physical or chemical change that requires (or absorbs) heat

energy

Photosynthesis is an endothermic reaction

(requires energy input from sun)

reaction

Endothermic reaction - Endothermic reaction - heat is taken in and the heat is taken in and the temperature may droptemperature may drop

Reactants Products

AB A + B

Breaking a Chemical Bond - Absorbs Energy

ENDOTHERMIC EXAMPLES

Baking bread

Cooking an egg

Photosynthesis

Melting Ice

Cold packs from nurse