balancing equations november , 2.009 *10 3
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Balancing EquationsNovember , 2.009 *103 Objective:
SWBAT apply law of conservation of mass to chemical reactions by balancing!
Catalyst: Name the reactants in this equation.
Fe + AlOH3 FeOH2 _+ Al Name the products in this equation.
2H2 + O2 2H2O
121
Agenda
Catalyst Go over test! Balancing Equations Practice Exit Question
Whiteboard Practice
How many atoms are in these compounds?
AlCl3 H2O H2O2
KCl Be3S2
Balancing equations RULES!
Key Point #1: When balancing equations, Never, Never, NEVER change subscripts, only coefficients!
Yo, Mr. Jhaveri
What is a coefficient?
GOOD QUESTION!
Coefficient
A coefficient is a whole number comes in front of the compound, never in the middle!
You multiply the coefficient to all the numbers in the compound
2AlCl3
Do you get it?
3AlCl3
How many atoms of each element do they have?
3 Aluminum’s 9 Chlorine’s
Whiteboard Practice
2AlCl3 4H2O 6H2O2
5KCl 2Be3S2
Why is the top equation wrong? (5 minutes) – You figure it out We never want to leave an equation
written like this… H2 + O2 H2O
We want to have it like this… 2H2 + O2 2H2O
WHY???
L-C-M!!!
Key Point #2: Chemical reactions MUST follow the
law of conservation of mass.
What was that LCM again?
If 3 carbons are in the reactants of a reaction, then there darn well better be 3 carbons in the products of a reaction.
Balancing Chemical Reactions
H2 + O2 H2O
__H____O__
Write down elements.
Balancing Chemical Reactions
H2 + O2 H2O
__H____O__
How many are there?
Balancing Chemical Reactions
H2 + O2 H2O
_2_H_2___O__
How many are there?
Balancing Chemical Reactions
H2 + O2 H2O
_2_H_2__2_O_1_
How many are there?
Balancing Chemical Reactions
Try These:N2 + H2 NH3
P4O10 + H2O H3PO4 Ca3P2 + H2O Ca(OH)2 + PH3
Balancing Chemical Reactions
Try These:N2 + 3H2 2NH3
P4O10 + H2O H3PO4 Ca3P2 + H2O Ca(OH)2 + PH3
Balancing Chemical Reactions
Try These:N2 + 3H2 2NH3
P4O10 + 6H2O 4H3PO4 Ca3P2 + H2O Ca(OH)2 + PH3
Balancing Chemical Reactions
Try These:N2 + 3H2 2NH3
P4O10 + 6H2O 4H3PO4 Ca3P2 + 6H2O
3Ca(OH)2 + 2PH3
Independent Practice
Worksheet!
Exit Question
Balance the following equations:
KClO3 ---> KCl + O2
S8 + O2 ---> SO3
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