Correct Net Ionic Equations | Eliminate Spectator Ions | Homework Help

[Qube]

Homework Statement

Which of the following is a correctly written net ionic equation?

http://i.minus.com/jYaipNE1rlRic.png

Homework Equations

Net ionic equation eliminate all spectator ions.

The Attempt at a Solution

It looks to me as if four of the answer choices are correct. All but one eliminate the spectator ions. How do I distinguish among the answer choices?

 

[Borek]

It is not only about spectator ions, think harder.

How do you think, is the first equation correct?

 

[Qube]

I think I see it now.

Choice 1) That's not sulfate. Sulfate has a -2 charge.

2) All nitrates are soluble so the left and right hand sides of that equation are the same thing/can be represented with either the subscript, (aq), or as individual ions.

3) Everything here is correct. No incorrect polyatomic ions, and a precipitate actually forms, as most fluorides are insoluble (CaF2, MgF2, etc.)

4) Not a net ionic equation. No ions written, for one thing.

5) All sulfates are soluble except sulfate compounds containing Ca, Ba, Sr, Hg, Ag, or Pb. Zinc sulfate is soluble.

 

[Keipi]

Which one do you then think is wrong?

As a tip, try writing all of the complete ionic equation first and indicate all of the phases. Then look at which of the ions remain in the same phase to write the net ionic equation. You should be able to figure out which ones are wrong and which ones are right at that point.

As an example:

Reaction: Mg (s) + 2 HCl (aq) --> MgCl₂ (aq) + H₂ (g)
Complete ionic equation: Mg (s) + 2 H⁺ (aq) + 2 Cl^- (aq) --> Mg²⁺ (aq) + 2 Cl^- (aq) + H₂ (g)

Cl^- is the only ion that stays in the same phase on both sides of the reaction so we can take that out of the equation, the net ionic equation will then be:

Net ionic equation: Mg (s) + 2 H⁺ (aq) --> Mg²⁺ (aq)+ H₂ (g)