Need help with some net ionic equations for AP chemistry?

Question

I am stuck on these problems and my textbook barely mentions anything about net ionic equations. Does anyone know the net ionic equation for the following:

1) Solid calcium carbonate is heated in a vacuum.
2) Equal volumes of equimolar solutions of phosphoric acid and calcium hydroxide are mixed.
3) Powdered strontium oxide is added to distilled water.
4) Chlorine gas is bubbled through a solution of potassium bromide.
5) Carbon monoxide gas is passed over hot iron(III) oxide.

Also, what is the significance of distilled water in net ionic equations? I have a couple net ionic equations regarding distilled water...And if you have any helpful websites on net equations, please give me the link. Thanks!

Answer 1

1) CaCO3 ---> CaO + CO2
(a decomposition reaction since in a vacuum no other elements can react with it. Carbonates always decompose to and oxide and CO2)

2) 2 H3PO4 + 3 Ca(OH)2 ---> 6 H2O + Ca3(PO4)2
(acid-base neutralization. Since aqueous there will be ions)
The net ionic for this is:
6 H+ + 6 OH- ---> 6 H2O
reduced: H+ + OH- ---> H2O
This is because the other ions would remain dissolved in soulution, but the H+ and OH- ions were removed from the solution to form liquid H2O. Acid-base reactions always have this as the net ionic

3) SrO + H2O ---> Sr(OH)2
Metallic oxides of alkali and alkaline earth elements react with water to produce metallic hydroxides.

4) Cl2 + 2 KBr ---> 2 KCl + Br2
since the K+ remains in solution, the only things changing are the Cl2 and the Br-
the net ionic is:
Cl2 + 2 Br- ---> 2 Cl- + Br2

5) 3 CO + Fe2O3 ---> 3 CO2 + Fe
oxidation-reduction process to purify iron in industry

Distilled water is important because it contains no other ions to add to the reaction. It is pure H2O with nothing else added.


All of these should be found in any good AP text. They are in the text I use: "Chemistry, the Central Science" by Brown, LeMay, Burston published by Prentice Hall

Answer 2

H2SO3 + NaOH --> Na2SO3 + H2O net ionic = 2H+ + OH- --> H2O(l) an acid/base rxn yields the aqueous salt and water as the precipitate d