[vickca86]

I'm desperate here.... I'm having a really hard time with chemical reactions. Any help would be appreciated.

Cu(NO3)2 + NH3 ----> ?

This would be a single displacement reaction right? I'm confused because in the experiment a precipitate formed and my understanding is that it must be a double displacement reaction for a precipitate to form.

Consider A + BC -----> B + AC

A = NH3, B = Cu and C = (NO3)2

unless AB + CD ----> AD + CB

A = Cu, B = (NO3)2, C = N, and D = H3 but I thought that since NH3 is a compound it wouldn't be separated into its individual elements....

Again any help would be appreciated.... My brain will not allow me to move on until I comprehend this....

[Borek]

Hint: precipitate doesn't contain ammonia (nor nitrogen from ammonia, not hydrogen from ammonia).

What do you know about ammonia solutions? pH?

[vickca86]

OK, so the precipitate would be copper? Even if the precipitate is copper I don't understand why there was a precipitate because as far as my untrained eye can tell this is a single displacement reaction and those don't form precipitates.

[Borek]

No, it wasn't copper. it was a copper compound.

You have ignored my question about properties of the ammonia solution - and that's the key to the answer.

[vickca86]

Sorry, I didn't mean to ignore your question about ammonia solutions. I'm in a bit of a jumble right now, chemical reactions are making little to no sense to me and I'm stressing the heck out...

So NH3(aq) suggests a base composition of NH4+ OH- so would it be Cu(NO3)2 + NH4OH or would it be Cu(NO3)2 + NH3 + H20?

[Hunter2]

One Hint. Ammonia is a base and its also a complexing agent.

[Borek]

So NH3(aq) suggests a base composition of NH4+ OH-

OH^- is the key to the answer.

its also a complexing agent.

It is an antyhint, as it doesn't matter when it comes to why the precipitate appears.

[Hunter2]

It is an antyhint, as it doesn't matter when it comes to why the precipitate appears.

Why?

The first question was what happens if ammonia and copper nitrate mixed together.

First it precipitates correct. 

But what happens if more ammonia is added, a dark blue solution appears. So what is wrong with it.

[Borek]

Have you read the first post? OP did an experiment and noticed precipitate. Question OP asks now is "what is the precipitate?" We don't discuss further changes now, so the information about ammonia being complexing agent is not helpful, it just confuses the OP even more.

[vickca86]

Thanks for pointing me in the right direction Borek

Cu(NO3)2(aq) + 2NH3(aq) ----> Cu(OH)2(s) + 2NH4NO3(aq)

On another note, I took my second chem test today and I thought there would be chemical reactions on it so that is mostly what I studied and there wasn't a single reaction on there.... The good thing is the material we were tested over was pretty straight forward stuff to me so I'm 90% sure I did well. I say 90% because I was 100% sure I did well on the first test and I bombed it, but I attribute that to my rusty algebra skills and careless use of significant figures....

[Borek]

Cu(NO3)2(aq) + 2NH3(aq) ----> Cu(OH)2(s) + 2NH4NO3(aq)

While there is a grain of truth in what you wrote, you won't be able to balance the equation, as list of reactants is not complete.