Download Chemical Reactions

Chemical Reactions
Chemical Reactions
• New Substances produced by changing the way atoms are
arranged
• Physical Changes ≠ Chemical Reaction
• Evidence
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Change in Color (rust)
Temperature Change (endo/exo-thermic)
Formation of a Gas
Formation of a Solid (Precipitate)
Chemical Equation
• Uses chemical formulas and symbols to describe a
chemical reaction and the product it produces (see
below)
Symbol
Meaning
Symbol
Meaning
Produces or Yields
(aq)
Aqueous
+
Plus
Heat
Reactants heated
(s)
Solid
Light
Reactants exposed
to light
(l)
Liquid
Elec
Electric current
applied to reactants
(g)
Gas
• 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
Reaction Classifications
Synthesis
…Combining Elements…
A new compound is formed by combining simpler reactants
A + B  AB
Mg + O2  MgO
Decomposition
…Separating Elements…
A reactant breaks down into simpler products (opposite of synthesis)
CD  C + D
H2O  H2 + O2
Combustion
…FIRE! (Needs Oxygen and produces CO2 )…
EF + O2  H2O + CO2
CH4 + O2  H2O + CO2
Single Replacement
…Switch out ONE element with another in a compound!...
GH + I  GI + H
CuCl2 + Zn  ZnCl2 + Cu
Double Replacement
…Switch Out Two Elements with Two Others!...
JK + LM  JM + KL
AgNO3 + HCl  AgCl + HNO3
Rate of Reaction
• Concentration
• High Concentration = faster reaction
• 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…
Rate of Reaction (Cont’d)
• Catalyst
• Something that speeds up the rate of reaction without being
affected itself.
• Inhibitor
• Something that slows down the rate of reaction without being
affected itself.
(Stop Here)
The Law of Conservation of Mass
• Matter Can Neither Be Created Nor Destroyed
• Reactants and Products MUST be EQUAL!
So…
We Balance Chemical Equations!
Videos!
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Alkali Metals in Water (3 min)
Sodium in Water (1 min)
Francium Bomb in Ocean (30 sec)
Chemistry Explosions (13 min)