Chem Homework Help?

Question

Ca + H20 >>>>
ZnCO3 + H3PO4 >>>>
FeSO4 + (NH4)2S >>>>

Also I wanted to check if Cl2 + NaBr has no reation.
Thanks alot...

Answer 1

1.) Ca + H2O ----> No reaction. Calcium just dissolves.

2.) The key here is to note that PO4 has a charge of 3-, CO3 has a charge of 2-, so Zn is 2+.
3 ZnCO3 + 2H3PO4 ---> 3H2(CO3) + Zn3(PO4)2

3.) SO4 is 2-, and NH4 is 1+. That means S is 2- here, and Fe is 2+.
FeSO4 + (NH4)2S ----> FeS + (NH4)2SO4

Cl2 + 2NaBr reacts to substitute the Cl for Br. Remember, atomic compounds in the same group (column) of the periodic table are more reactive as it goes up the table, so Cl is more reactive than Br.
Cl2 + 2NaBr -----> NaCl2