Predicting Products?

Question

Could you tell me HOW and what the answers are for these? I want to know how because there are other problems like it.

A) the type of reaction that occurs
B) predict the products of the reaction
C) write a balanced chemical equation

aluminum metal + calcium phosphate ->

Answer 1

Al + Ca3(PO4)2 -->

1) This is a single replacement reaction. It follows the general pattern of:
A + BC --> AC + B

In this reaction aluminum makes positive ions (as all metals do), and in the compound calcium phosphate, calcium is a positive ion and the phosphate polyatomic ion is negative. In this type of reaction the positive ions will change places.

B) Al + Ca3(PO4)2 --> AlPO4 + Ca

(In this reaction, Al makes a 3+ ion, Ca makes a 2+ ion and (PO4) makes a 3- ion. Cross over your oxidation numbers in your compound to get your subscripts for both your reactants and your products.

You balance your equation.

CHEMISTRY TEACHER

Answer 2

Carol P has a good answer. I would just add that, when predicting products, one needs to determine if a product will be formed at all, ie will you get a precipitate.

Then you need to use the solubility chart like the one found at the following site:
http://intro.chem.okstate.edu/1515SP01/Database/Solub.html

Sometimes we add two reactants together and we don't see a reaction since they do not change in the presence of one another.