Exothermic and Endothermic

Reactions

It’s a give and take It’s a give and take relationship!!!!relationship!!!!

Every Reaction Involves EnergyEvery Reaction Involves Energy

1.1. During a reaction…bondsDuring a reaction…bonds absorb energy and breakabsorb energy and break2.2. New bonds form…energyNew bonds form…energy releasedreleased

Symbols In Chemical ReactionsSymbols In Chemical Reactions

Symbols In Chemical ReactionsSymbols In Chemical Reactions

Heat is given off Heat is given off

Light EnergyLight Energy

Electrical EnergyElectrical Energy

Thermal EnergyThermal Energy

What Is A Chemical Reaction?What Is A Chemical Reaction?

• Chemical ReactionChemical Reaction: the process : the process by which one or more substances by which one or more substances undergo change to produce one undergo change to produce one

or more different substancesor more different substances

How To Identify A Chemical Reaction How To Identify A Chemical Reaction Has Occurred Or Is HappeningHas Occurred Or Is Happening

1. Gas Formation1. Gas Formation

3. Color Change3. Color Change 4. Energy Change4. Energy Change

2. Solid Formation2. Solid Formation

Parts To A Chemical ReactionParts To A Chemical Reaction

CC OO22 COCO22

1.1.ReactantsReactants: starting materials of a: starting materials of achemical reactionchemical reaction

2.2.ProductsProducts: substances formed : substances formed

Chemical Reaction 2Chemical Reaction 2

2Na2Na ClCl22 2NaCl2NaCl

What Do You Notice About All The What Do You Notice About All The Atoms?Atoms?

Chemical Reactions Must Be Chemical Reactions Must Be Balanced!!!!Balanced!!!!

It’s a Law!!!!!!!!!!!It’s a Law!!!!!!!!!!!

The Law Of The Law Of Conservation Of Conservation Of

MassMass

**Mass is neither **Mass is neither created nor destroyed created nor destroyed in ordinary chemical in ordinary chemical reactionsreactions

Exothermic ReactionsExothermic Reactions• Chemical Reaction in which energy Chemical Reaction in which energy

is is releasedreleased or or removedremoved

2 Na + Cl2 Na + Cl22 2 NaCl + Energy 2 NaCl + Energy

Energy is Energy is in the in the

products in products in an an

Exothermic Exothermic ReactionReaction

Endothermic ReactionsEndothermic Reactions

• Chemical reaction in which energy Chemical reaction in which energy is is absorbedabsorbed

6 CO6 CO2 2 + 6 H+ 6 H22O + Energy O + Energy C C66HH1212OO66 + 6 0 + 6 022

Energy is in the Energy is in the reactants in an reactants in an

Endothermic Reaction Endothermic Reaction