Chemistry: Precipitation Reactions?

Question

Happy 2007 to everyone...

I have 3 chemistry that are all very similar but I do not understand the meaning behind it or how to solve it even with the solution manual's answer. I was wondering if someone could explain it to me. Thank You.

Q: All the molecular equations below have the same net ionic equation in aqueous solution except:

1. HI + KOH --> H2O + KI
2. HNO3 + NaOH --> H2O + NaNO3
3. HF + NaOH --> H2O + NaF

A: 3

Q: All the following acid-base reactions have the same net ionic equation except:

1. HF + RbOH
2. HClO4 + KOH
3. HNO3 + NaOH

A: 1

Q: All the reaction below have the same net ionic equation except:

1. NaOH + HBr
2. RbOH + HF
3. BA(OH)2 + HI

A: 2

Answer 1

I'm puzzled by the answers and don't consider them correct.

A net ionic reaction is one where all the spectator ions will be eliminated.

In the first question the net ionic reaction for all three reactions is:
H+ + _OH --> H2O
so they are all the same.

In the second question, the net ionic reactions are also all:
H+ + -OH --> H2O

Same thing for the third question.

None produce gases or solid precipitates. All alkali metal salts are soluble. The last equation of the third question has Barium hydroxide, which is a solid precipitate, but even it will have a reaction to produce water although it will be somewhat slow.

Answer 2

I think, although I'm not entirely sure: 2NaOH + CuSO4 ---> Cu(OH)2 + Na2SO4 NaOH + AgNO3 ---> AgOH + NaNO3 NaOH + CoCl2 ---> Co(OH)2 + NaCl KI + AgNO3 ---> AgI + KNO3 Precipiation reactions are basically where you get an insoluble solid product as one of your products of the reaction. For example, for the first reaction I think you would get a blue precipitate.

Answer 3

they all have the same net ionic equations! maybe the question is focusing on something else? water is the percipitate in all of the reactions so H+ + OH- --> H2O. sorry.

Answer 4

Well the HF is the only weak acid in the list.