Writing the balanced equation.

First write out the formulas for the reactants in involved.
If you would have been a little observant you could have just copied the
formulas from the reagent bottles. If not than you need to write the formulas
form the names. I will help you on the first one, sodium carbonate. Look up the
symbols or polyatomic ions in the back of your book and keep in mind their
charge. Place the positive on first and the negative second. Determine what it
would take for the positive (cation) and negative (anion) to equal zero. In the
case of sodium carbonate, sodium is +1 and carbonate is –2. Therefore, sodium
(Na) need to be doubled for the one carbonate (CO_{3}). In the end we end up with the formula Na_{2}CO_{3}.

Do the same with the other reactant.

The next thing is to put the equation together. The format for equations follows a before and after set up. The reactants are the compounds before the reaction occur and the products are what is produced once reaction take place. This is indicated with the symbol “®” , the reactant and products are separated by a “+” sign. Remember the plus sign is just a separator.

The general out line of the reaction in question is called a double replacement reaction in with cations and anions swap.

AB + CD ® AD + CB