1. Chemical Reactions
New Substances produced by changing the way atoms are arranged
Physical Changes ≠ Chemical Reaction
Evidence
Change in Color (rust)
Temperature Change (endo/exo-thermic)
Formation of a Gas
Formation of a Solid (Precipitate)

2. Reactants: Substances Present @ Beginning
Products: Substances Formed by the Reaction
Yields: An “equal sign” in a chemical reaction meaning “produces”, “creates”, or “forms”…
Na Cl2  NaCl
Reactants Yields Products
Reactants
Product

3. Reaction Classifications

4. Synthesis A + B  AB Mg + O2  MgO …Combining Elements… Product
Reactants

5. …Separating Elements…
Decomposition
…Separating Elements…
CD  C + D
H20  H2 + O2
Reactants
Product

6. …FIRE! (Needs Oxygen and produces CO2 )…
Combustion
…FIRE! (Needs Oxygen and produces CO2 )…
EF + O2  H CO2 + HEAT
CH4 + O2  H CO2
Reactants
Product

7. …Switch out ONE element with another!...
Single Replacement
…Switch out ONE element with another!...
GH + I  GI + H
CuCl2 + Zn  ZnCl2 + Cu
Reactants
Product

8. …Switch Out Two Elements with Two Others!...
Double Replacement
…Switch Out Two Elements with Two Others!...
JK + LM  JM + KL
AgNO3 + HCl  AgCl + HNO3
(Stop Here)
Reactants
Product

9. Rate of Reaction Concentration Surface Area Temperature
High Concentration = faster reaction
The more particles – the more chance of collisions
Surface Area
More surfaces available to react = faster reaction
Temperature
Higher Temperatures = faster reaction
Particles speed up or slow down…speeding up or slowing down the reaction…

10. Rate of Reaction (Cont’d)
Catalyst
Something that speeds up the rate of reaction without being affected itself.
A good example is the way the platinum catalyst in a car’s catalytic converter works to change toxic carbon monoxide into less-toxic carbon dioxide.
Inhibitor
Something that slows down the rate of reaction without being affected itself.

11. The Law of Conservation of Mass
Matter Can Neither Be Created Nor Destroyed
Reactants and Products MUST be EQUAL!

12. Endothermic Reactions
Endothermic reactions are reactions which take energy in from their surroundings.
If a substance is undergoing an endothermic reaction would it’s surroundings get warmer or colder?
It’s surroundings get colder.
Endothermic reactions occur when the bonds of a substance are being broken.

13. Useful Endothermic Reactions
When things dissolve they are undergoing an endothermic reaction.
Cooking is an endothermic reaction.
The food takes in the heat provided by the cooker.
The chemicals of the food undergo a chemical reaction which makes them easier to digest.
Cold packs for sports injuries rely on endothermic reactions.
When you twist or shake the pack the chemicals in the pack start reacting.
Because they undergo an endothermic reaction they take heat in from their surroundings.
This makes the pack cold.

14. Exothermic Reactions Exothermic reactions give off heat.
They occur when chemical bonds are formed.
If substances are undergoing exothermic reactions will their surroundings get hotter or colder?
The will get hotter.

15. Useful Exothermic Reactions
Combustion: all combustion reactions give off heat.
Neutralization reactions are exothermic.
Hot Pad hand warmers
When the hand warmer is shaken they chemicals inside undergo an exothermic reaction
This releases the heat which helps to warm up your hand.