1. Balancing Equations

2. 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.
Na + Cl2  NaCl 2 2

3. What you can not do!
You can NOT change the formula of the molecules I give you.
H2 + O2  H2O
you cannot change water to H2O2 (hydrogen peroxide)
If the number is one, you
don’t have to write it! 2 2
and this will make 2
water molecules
you have to increase the
amount of H on this side H H O O H O  H H H O H H

4. What you are allowed to do
change the coefficient in front of any molecule/atom (changing the ratio of atoms)
___ Ag + ___ Cl2  ___ AgCl
you can only write on those lines 2 2

5. Problem solving strategies
It helps to make a list of all atoms present
HCl + Ba(OH)2  BaCl H2O 2 2
Ba – 1
H – 3
Cl – 1
O – 2
Start making the
numbers agree
one at a time
(pick something,
that occurs in only
one molecule 1st)
~not H in this case
Ba – 1
H – 2
Cl – 2
O – 1
Now going
to O 4 2 4 2
Now everything
is balanced!
starting w/ Cl

6. Another to try CH4 + O2  H2O + CO2 2 2 C- 1 C- 1 H- 4 H- 2 O- 2 O- 3
Everything is balanced now!
This takes a lot of trial and error.
Start with H
now O

7. More Practice 2
NH4ClO CaSO4  Ca(ClO3) (NH4)2SO4

8. Common multiples
P + Cl2  PCl3

9. Another
HClO3 + Sc  Sc(ClO3) H2

10. Homework
HNO3 + Zn  H2 + ZnNO3