How to balance the chemical equation of copper nitrate with sodium?

First we start off by making the first part of the
equation: Copper Nitrate plus Sodium: Cu(SO3)2 + Na

This
reaction is a single replacement one. Na (Sodium) is a metal so it has a positive charge
which means it is going to react with the part of Copper Nitrate that has a Negative
charge. It's going to react with the nitrate ion because copper is positive and it can't
react with it. 

Since nitrate is reacting with sodium
:

Nitrates charge is
+1 

Sodiums charge is +1

You
get NaSo3 +Cu

Now you have both the reactants and the
product. all you have to do is balance them:

Cu(SO3)2 +
Na--> NaSO3 + Cu

First you would see if copper is
balanced (it is) 

Then you see Nitrate is balance (its
not) 

On the reactant side you have 2
nitrate

and on the product side you have 1 so you have to
put a coefficient 2 in front of NaSO3

Cu(SO3)2 + Na
--> 2NaSO3 + Cu

Now sodium isnt balanced because
there is 2 on the product so you would put a 2 as a coefficient on the reactant
side:

Cu(SO3)2 + 2Na --> 2NaSO3 + Cu
 

AND NOW ITS BALANCED