Balancing Equations - Copley

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Transcript Balancing Equations - Copley

Balancing Equations
Chapter 6
What is balancing an equation?
Balancing an equation is changing the
ratios of molecules/atoms to make the
lowest possible same whole number
and type of atoms on each side of the
equation.
2 Na + Cl2 2 NaCl
What you can not do!
You can NOT change the formula of the
molecules I give you.
If the number is one, you
2H2 + O2  2 H2O don’t have to write it!
you cannot change water to H2O2
and this will make 2
(hydrogen peroxide)
you have to increase the
amount of H on this side
H H
O O

H
O
water molecules
H
H
H H
O
H
What you are allowed to do
change the coefficient in front of any
molecule/atom (changing the ratio of
atoms)
2 Ag + ___ Cl  ___
2 AgCl
___
2
you can only write on those lines
Problem solving strategies
It helps to make a list of all atoms
present
2 HCl + Ba(OH)2  BaCl2 + 2 H2O
Ba – 1
H–3 4
Cl – 1 2
O–2
starting w/
Cl
Start making the Ba – 1
numbers agree
H–2 4
one at a time
(pick something, Cl – 2
that occurs in only O – 1 2
one molecule 1st)
~not H in this case
Now going
to O
Now everything
is balanced!
Another to try
CH4 + 2O2 
C- 1
H- 4
O- 2 4
Start with H
now O
2 H2O + CO2
C- 1
H- 2 4
O- 3 4
Everything is balanced now!
This takes a lot of trial and error.
More Practice
2 NH4ClO3 +
CaSO4 
Ca(ClO3)2 +
(NH4)2SO4
Common multiples
2 P + 3 Cl2  2 PCl3
Another
6 HClO3 +2 Sc 2 Sc(ClO3)3 +3 H2
Homework
HNO3 + Zn  H2 + ZnNO3