Post on 04-Jan-2016
Chemical Reactions
New Substances produced by changing the way atoms are arranged
Physical Changes ≠ Chemical ReactionEvidence
Change in Color (rust)Temperature Change (endo/exo-thermic)Formation of a GasFormation of a Solid (Precipitate)
Chemical Reactions
Reactants: Substances Present @ BeginningProducts: Substances Formed by the ReactionYields: An “equal sign” in a
chemical reaction meaning “produces”, “creates”, or “forms”…
Na + Cl2 NaCl
Reactants Yields Products
Reaction Classifications
…Combining Elements…
A + B AB
Mg + O2 MgO
Synthesis
…Separating Elements…
CD C + D
H2O H2 + O2
(+Electricity)
Decomposition
…FIRE! (Needs Oxygen and produces CO2 )…
EF + O2 H2O + CO2
CH4 + O2 H2O + CO2
Combustion
…Switch out ONE element with another!...
GH + I GI + H
CuCl2 + Zn ZnCl2 + Cu
Single Replacement
…Switch Out Two Elements with Two Others!...
JK + LM JM + KL
AgNO3 + HCl AgCl + HNO3
(Stop Here)
Double Replacement
ConcentrationHigh Concentration = faster reaction
Surface AreaMore surfaces available to react = faster reaction
TemperatureHigher Temperatures = faster reaction
Particles speed up or slow down…speeding up or slowing down the reaction…
Rate of Reaction
CatalystSomething that speeds up the rate of reaction
without being affected itself.
InhibitorSomething that slows down the rate of
reaction without being affected itself.
(Stop Here)
Rate of Reaction (Cont’d)
Matter Can Neither Be Created Nor Destroyed
Reactants and Products MUST be EQUAL!
So…
We Balance Chemical Equations!
The Law of Conservation of Mass
Adding Coefficients to Reactants and Products in order to make both sides of the arrow EQUAL!
Na + Cl2 NaCl
Reactants Yields Products
This Chemical Equation is WRONG! (Why??)Na: 1 Na: 1
Cl: 2 Cl: 1The Numbers of Atoms are not BALANCED!
Balancing Equations
So….We add Coefficients to Make the Equation Balanced! We can NEVER EVER Add or Take
Away Subscripts! EVER!!
Na + Cl2 NaClNa: 1 Na: 1Cl: 2 Cl: 1
It is BALANCED!! WOO HOO!
Balancing Equations (cont’d)
So…My Balanced, Correct Chemical Reaction Between Sodium and Chlorine
is…
2Na + Cl2 2NaCl
This says that TWO atoms of sodium react with ONE diatomic molecule of
chlorine and produces TWO molecules of sodium chloride!
Balancing Equations (Cont’d)
H2 + O2 H2O
H: H:O: O:
Balancing: Your Turn
Start By Setting it Up Like This
H2 + O2 H2O
H: 2 H: 2O: 2 O: 1
Answer!
¿¿¿ ¿¿¿Questions ??? ???
Try to balance the following reactions! You may check with a partner as you work!
1. Mg + O2 MgO
2. N2 + H2 NH3
3. Cl2 + KI KCl + I2
4. Na + HCl H2 + NaCl
Balancing Practice
1. 2Mg + O2 2MgO
2. N2 + 3H2 2NH3
3. Cl2 + 2KI 2KCl + I2
4. 2Na + 2HCl H2 + 2NaCl
Balancing Practice – Answers!
Copy and complete the following flow map using your notes. Be sure to COLOR CODE to match your notes! Add extra reminder “bubbles” as you go!
How to Balance Chemical Equations
INB 93
1) Count the number of ATOMS on each side of the chemical
equationH2 + O2 H2O
H: 2 H: 2 O: 2 O: 1
2. Add Coefficients on each side of the equation so that…
3. …Continue…
Classifications 1 (1:30)Classifications 2 (1:30)
Alkali Metals in Water (3 min)Sodium in Water (1 min)Dry Ice Eruptions (11 min)Francium Bomb in Ocean (30 sec)Chemistry Explosions (13 min)
Videos!