Write the balanced formula equation, complete ionic equation, and net ionic equation. If no precipitate forms, write "No reaction"
a) Hg2(NO3)2 (aq) + CuSO4 (aq)
b) Ni(NO3)2 (aq) + CaCl2 (aq)
c) K2CO3 (aq) + MgI2 (aq)
d) Na2CrO4 (aq) + AlBr3
Please explain! Thank you
A reaction "goes" if one of three things happen.
a. a ppt forms,
b. a gas forms, or
c. a slightly ionized substance forms.
example c.
The balanced formula equation follows:
K2CO3(aq) + MgCl2(aq) ==> MgCO3(s) +
2KCl(aq)
For the complete ionic equation you separate all of the entities above into ions UNLESS the substance meets one of the three reasons why a reaction goes to completion. For any of the three above, you write the substance as molecules and not as ions.
2K^+(aq) + CO3^2-(aq) + Mg^2+(aq) + 2Cl^-(aq) ==> MgCO3(s) + 2K^+(aq) + 2Cl^-
Then we form the NET IONIC equation by canceling those ions common to both sides. That means we cancel 2K^+(aq) and 2Cl^-(aq) to leave the following:
Mg^2+(aq) + CO3^2-(aq) ==> MgCO3(s)
The ions you canceled are called spectator ions.
An example of a reaction that forms no ppt is b.
Obviously you need to know which salts are soluble. Here is a simplified table of solubility rules.
http://www.files.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html
2mg(s)+o2(g)=2mgo(s)
a) Hg2(NO3)2 (aq) + CuSO4 (aq)
1. Balanced formula equation:
Hg2(NO3)2 (aq) + CuSO4 (aq) → Hg2SO4 (s) + Cu(NO3)2 (aq)
2. Complete ionic equation:
2Hg2^2+(aq) + 4NO3^-(aq) + Cu^2+(aq) + SO4^2-(aq) → 2Hg2SO4 (s) + 2Cu^2+(aq) + 4NO3^-(aq)
3. Net ionic equation:
2Hg2^2+(aq) + SO4^2-(aq) → Hg2SO4 (s)
b) Ni(NO3)2 (aq) + CaCl2 (aq)
1. Balanced formula equation:
Ni(NO3)2 (aq) + CaCl2 (aq) → NiCl2 (aq) + Ca(NO3)2 (aq)
2. Complete ionic equation:
Ni^2+(aq) + 2NO3^-(aq) + Ca^2+(aq) + 2Cl^-(aq) → NiCl2 (aq) + Ca^2+(aq) + 2NO3^-(aq)
3. Net ionic equation:
Ni^2+(aq) + 2Cl^-(aq) → NiCl2 (aq)
c) K2CO3 (aq) + MgI2 (aq)
1. Balanced formula equation:
K2CO3 (aq) + MgI2 (aq) → 2KI (aq) + MgCO3 (s)
2. Complete ionic equation:
2K^+(aq) + CO3^2-(aq) + Mg^2+(aq) + 2I^-(aq) → 2K^+(aq) + 2I^-(aq) + MgCO3 (s)
3. Net ionic equation:
CO3^2-(aq) + Mg^2+(aq) → MgCO3 (s)
d) Na2CrO4 (aq) + AlBr3 (aq)
1. Balanced formula equation:
Na2CrO4 (aq) + AlBr3 (aq) → NaBr (aq) + Al(CrO4)3 (s)
2. Complete ionic equation:
2Na^+(aq) + CrO4^2-(aq) + 2Al^3+(aq) + 6Br^-(aq) → 2Na^+(aq) + 2Br^-(aq) + Al(CrO4)3 (s)
3. Net ionic equation:
CrO4^2-(aq) + 2Al^3+(aq) → Al(CrO4)3 (s)
In all the cases where a solid is formed, the net ionic equation represents the reaction after eliminating the spectator ions, which are present in the complete ionic equation but do not participate in the actual chemical reaction. If no solid is formed, it means there is no precipitation, and the reaction is considered a "no reaction".
a) The balanced formula equation for a) is:
Hg2(NO3)2 (aq) + CuSO4 (aq) -> Hg2SO4 (s) + Cu(NO3)2 (aq)
To balance the equation, we need to make sure that the number of atoms of each element is the same on both sides of the equation. Here's how we can balance the equation:
1. Balance the mercury (Hg) atoms: There are two Hg atoms on the left side and one on the right side. Multiply the Hg2(NO3)2 compound by 2:
2 Hg2(NO3)2 (aq) + CuSO4 (aq) -> Hg2SO4 (s) + Cu(NO3)2 (aq)
2. Balance the nitrate (NO3) ions: There are four NO3 ions on the left side and two on the right side. Multiply the Cu(NO3)2 compound by 2:
2 Hg2(NO3)2 (aq) + CuSO4 (aq) -> Hg2SO4 (s) + 2 Cu(NO3)2 (aq)
The complete ionic equation shows all the ions in the reaction:
2 Hg2^2+ (aq) + 4 NO3^-(aq) + Cu^2+ (aq) + SO4^2-(aq) -> Hg2SO4 (s) + 2 Cu^2+(aq) + 4 NO3^-(aq)
Finally, the net ionic equation removes the spectator ions (ions that are present on both sides of the equation without undergoing any change):
2 Hg2^2+ (aq) + SO4^2-(aq) -> Hg2SO4 (s)
b) The balanced formula equation for b) is:
Ni(NO3)2 (aq) + CaCl2 (aq) -> NiCl2 (aq) + Ca(NO3)2 (aq)
The complete ionic equation is:
Ni^2+(aq) + 2 NO3^-(aq) + Ca^2+(aq) + 2 Cl^-(aq) -> NiCl2 (aq) + Ca^2+(aq) + 2 NO3^-(aq)
The net ionic equation is:
Ni^2+(aq) + 2 Cl^-(aq) -> NiCl2 (aq)
c) The balanced formula equation for c) is:
K2CO3 (aq) + MgI2 (aq) -> 2 KI (aq) + MgCO3 (s)
The complete ionic equation is:
2 K^+(aq) + CO3^2-(aq) + Mg^2+(aq) + 2 I^-(aq) -> 2 K^+(aq) + 2 I^-(aq) + MgCO3 (s)
The net ionic equation is:
CO3^2-(aq) + Mg^2+(aq) -> MgCO3 (s)
d) Since no precipitate forms, we can write "No reaction."