[Mr. Raru]

This is from a 1992 AP chem reaction:

An excess of nitric acid solution is added to a solution of tetraaminecopper(II) sulfate.

What is the net ionic equation without balancing?

In class, my teacher said:

H⁺ + Cu(NH₃)₄⁺² + SO₄^-2 -----------------------> Cu⁺² +NH₄⁺ + HSO₄^-1

But when I searched online, numerous sources sad:

H⁺ + Cu(NH₃)₄⁺²  -----------------------> Cu⁺² +NH₄⁺

Which one is correct? And why?
Since there is excess nitric acid, I understand why my teacher said the hydrogen sulfate ion would form after the ligand was removed, but I am questioning the formation of HSO₄^-1.

[Alberto_Kravina]

Those two reaction equations are not balanced.
I think that the correct reaction equation would be:

[Cu(NH₃)₄ ]SO₄ + 4 HNO₃ --------> 4 NH₄NO₃ + CuSO₄

and maybe the copper sulfate reacts with nitric acid to form hydrogen sulfate ions ( could be something like this : CuSO₄+HNO₃->CuNO₃⁺ + HSO₄^- sounds a bit weird neh?) ...

However, I think that the first reaction is more likely.

[Borek]

I am questioning the formation of HSO₄^-1.

HNO₃ is stronger acid than HSO₄^-.

[Mr. Raru]

hmm... Im not quite sure I follow. Alberto, my equations are net ionic with spectator ions removed and the question did not require balancing. So if I eliminated the spectator ions from your first equation, I would have got my same net ionic equation. My question is would the sulfate ion react with the hydrogen ion to form the bisulfate ion?

HNO₃ is stronger acid than HSO₄^-.

I know this, but how does it affect the formation of HSO₄^-

[Toutetsu]

Maybe this is just me being weird, but as far as I can tell the NH₃ has no ion.

So, this

NH₄NO₃

would be a -1.

The one that comes to me is

2H⁺ + 2NO₃^- + Cu(NH₃)₄²⁺ + SO₄^2- -----> Cu(NH₃)₄(NO₃)₂ + H₂SO₄

Going along with that, since the NH₃ is not ionized, I don't see any reason why it would change. Also, the only thing that I can find wrong with this is that all of the products are soluble, so the final answer would be "No net reaction".

I happen to be using this problem for a Christmas assignment, and I know that its a complex ion, so the final answer has to have 1+ molecules/ions bonded to a central metal ion.

[Borek]

Maybe this is just me being weird, but as far as I can tell the NH₃ has no ion.

NH₃ + H⁺ <-> NH₄⁺

[Toutetsu]

Sorry, I should have said that I see no reason for the NH₃ to ionize.

[AWK]

Sorry, I should have said that I see no reason for the NH₃ to ionize.

Why - nitric acid is a strong acid, ammonia is a weak base - the should react.

Both reactions given by Mr Raru are correct - the first one concerns sulfate, the second one may concern nitrate for example

[Toutetsu]

Ok. That makes more sense.

The reaction that my teacher finally gave me was

4H⁺ + Cu(NH₃)₄²⁺ ------> 4NH₄⁺ + Cu²⁺

Since both the sulfate and the nitrate are spectators, we ignore them and simplify it down to that.

[AWK]

Ok. That makes more sense.

The reaction that my teacher finally gave me was

4H⁺ + Cu(NH₃)₄²⁺ ------> 4NH₄⁺ + Cu²⁺

Since both the sulfate and the nitrate are spectators, we ignore them and simplify it down to that.

Sulfate in strong acids forms hydrogen sulfate!

[Toutetsu]

Ok. That makes more sense.

The reaction that my teacher finally gave me was

4H⁺ + Cu(NH₃)₄²⁺ ------> 4NH₄⁺ + Cu²⁺

Since both the sulfate and the nitrate are spectators, we ignore them and simplify it down to that.

Sulfate in strong acids forms hydrogen sulfate!

But the SO₄^2- is aqueous on both sides of the reaction, and is therefore ignored.

[AWK]

In the presence of strong acids SO₄^2- form HSO₄^-