Net Ionic Equations for Common Chemical Reactions: Examples and Solutions

[ksinclair13]

Alright, these were asked on the test I took today, and I was just seeing if I did them correctly.

Write the net ionic equations for the following reactions (don't need to be balanced):

1. Solid potassium amine is added to distilled water.

KNH₂ + H₂O ---> K⁺ + NH₃ + OH^-

2. Sulfur dioxide gas is bubbled through distilled water.

SO₂ + H₂O ---> H₂SO₃

3. Nickel nitrate is mixed with sodium sulfide.

Ni⁺ + S^2- ---> Ni₂S

4. Phosphorous trihydride is combined with boron tricloride.

PH₃ + BCl₃ ---> BH₃ + PCl₃

For the first one, I'm thinking it might be NH₄⁺ on the products side instead of NH₃...? I'm not that confident about the second one, and I think I nailed the third one, but maybe not. For the last one, I didn't know if it would be a double replacemnet or if it would form one big molecule...If anyone notices any mistakes, big or small, please point them out =). This is my worst part of chemistry :-(

 

[Borek]

Ni²⁺.Borek

 

[ksinclair13]

Oh okay, thank you. So everything else is surprisingly correct then? Or were you just pointing out that one mistake?

Aluminum metal is washed with excess distilled water.

Al + H₂O ---> [Al(H₂O)₆]³⁺

or would it simply be:

Al + H₂O ---> Al(OH)₃ + H₂

An unknown weak monoprotic acid is titrated using a standard strong base. The titration curve will be as follows:

A. Rapid increase and then no sharp increase
B. Gradual increase and then a sharp increase
C. ...
D. ...
E. ...

The wording is kind of messed up here. Both are sort of correct. There will be a small rapid increase initially, but then there is a sharp increase (not AS sharp as a strong acid-strong base titration, but still sharp) when it nears the equivalence point.

You could also argue that it gradually increases and then there is that sharp increase that I was talking about. However, that sounds more like a strong acid-strong base. Therefore, I guessed A, knowing that either could technically work.

Any more help is greatly appreciated!

 

[Borek]

1st probably OK, 2nd OK for sure, no idea about 4th.

Al doesn't react with distilled water, it is passivated with Al2O3.

Your thinking about AB wording sounds correct, it can be argued they are both OK or both wrong.Borek

 

[ksinclair13]

Thank you again! My teacher makes his tests exactly like the AP Test, except half as long. They are very difficult, which means he makes a big curve, so I always get an A :).

 

[stamba]

Reply

Hi.
1. Correct!

2. Correct!

3. Ni2+ + S2- --> NiS(s)
NiS is solid black substance. It doesn't dissolve in water.

4. PH3 + BCl3 --> PH3BCl3
PH3BCl3 is solid, PH3 and BCl3 are gasses.