complete and balance the following chemical equations H3PO4+CaCO3?, K2SO4(aq)+Pb(NO3)2(aq)?, K3PO4+CaBr2(aq)?

Answer 1

I'm not going to do all of these for you, but you need to think about reactions that you've learned about in class or in your text book, and apply what you know to each of these reactions.

In the first one, you have carbonate ions in one of the reactants, and the other is an acid. Carbonate ions will react with H+ ions to form carbonic acid (H2CO3) which will decompose into water and CO2. You should also be able to recognize that Calcium phosphate will be an insoluble compound, and so will form a precipitate. So:

2 H3PO4 + 3 CaCO3 --> 3 H2O + 3 CO2 + Ca3(PO4)2

For your other two reactions, you will form a precipitate, and the other ions will just be spectator ions and will remain in solution. Think about what possible compounds you might form by combining ions from the two reactants, and you'll see that one compound will be insoluble, and so will precipitate.

Answer 2

2 H3PO4 (aq) + 3 CaCO3 (s) --> 3 H2O (l) + 3 CO2(g)+ Ca3(PO4)2 (s)

K2SO4(aq)+ Pb(NO3)2(aq) --------> 2KNO3(aq) + PbSO4 (s)

2K3PO4 (aq) + 3CaBr2(aq) ------------> 6KBr (aq) + Ca3(PO4)2 (s)