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Balancing Equations
Law of Conservation of Matter
Law of conservation of matter states
matter can not be created nor
destroyed… but, it can change forms
This means you must have the same
elements on both sides of a reaction
AND… it means you must have the same
number of atoms on both sides
Law of Conservation of Matter
You must have the same elements on
both sides of a reaction… what does
that part mean?
Well, when these two things react
ZnCl2 + Li 
the new things that are made must
have zinc, chlorine, and lithium!
(You can’t just create gold or iron)
Law of Conservation of Matter
AND… You must have the same number
of atoms on both sides… what does
that part mean?
Well, when these two things react
ZnCl2 + Li  LiCl + Zn
notice that the elements are the
same but… not the numbers.
(You can’t just lose or find atoms)
Balancing Equations
__ ZnCl2+ __ Li  __ LiCl + __ Zn
Rules for balancing:
1. Can only use coefficients (big
numbers in front of formulas)
2. Must have same number of each
element on each side
Balancing Equations
__ ZnCl2+ __ Li  __ LiCl + __ Zn
Step 1- make a list of each
element on each side
Left side Right side
Zn
Zn
Cl
Cl
Li
Li
Balancing Equations
__ ZnCl2+ __ Li  __ LiCl + __ Zn
Step 2- count the number of each
element on each side
Left side Right side
1 Zn
Zn 1
2 Cl
Cl 1
1 Li
Li 1
Balancing Equations
2 LiCl + __ Zn
__ ZnCl2+ __ Li  __
Step 3- start placing coefficients
in front to BALANCE out the
sides
Left side Right side
1 Zn
Zn 1
2 Cl
Cl /1 2
1 Li
Li 1
/ 2
Balancing Equations
2 Li  _2_ LiCl + __ Zn
__ ZnCl2+ __
Step 3- continue placing
coefficients in front to BALANCE
out the sides
Left side Right side
1 Zn
Zn 1
2 Cl
Cl 2
2 /1 Li
Li 2
Balancing Equations
__ ZnCl2+ _2_ Li  _2_ LiCl + __ Zn
Step 4- check to make sure that
both sides are balanced
Left side Right side
1 Zn
Zn 1
2 Cl
Cl 2
2 Li
Li 2
Balancing Equations
__ Mn + __ O2  __ MnO
Left side Right side
1 Mn
Mn 1
2 O
O 1
Balancing Equations
2 Mn + __ O2  __
2 MnO
__
Left side Right side
Mn 1
21
/ Mn
/ 2
/ 2
2 O
O 1
Balancing Equations
2 Li3P+__ Mg3N2  __
2 Li3N+__ Mg3P2
__
Left side Right side
6 3/ Li
Li /3 6
P 2
2 /1 P
3 Mg
Mg 3
2N
N /1 2