[Bel-p]

OK, it's me again with another question about predicting products of a reaction.  I found a worksheet on the internet (http://misterguch.brinkster.net/001_002.doc) with loads of equation questions, and I started with Section 3, Q1:

Predict the products of the following reaction:
1) Ag +  CuSO4 -->

OK, so the easy answer is to think that there must be a reaction otherwise they wouldn't be asking for the product, so the answer is AgSO4 + Cu, and then balance it:
2Ag + CuSO4 --> Ag2SO4 + Cu

BUT what I don't understand is why there's a reaction at all - Siver is less reactive (lower on the reactivity series) than copper so why does it react with SO4 and displace the copper?  I thought something only displace another element if the displacing element was more reactive than the other one. 

Am I missing something very basic?

[Borek]

OK, so the easy answer is to think that there must be a reaction otherwise they wouldn't be asking for the product

And that's where you are wrong

There is no reaction.

Please use charges whenever you refer to ions, and please refer to ions whenever you are talking about water solutions

[Bel-p]

Aha, so I was right to think there shouldn't be a reaction - hurray and what a relief!

In that case it's a bit worrying that it's on a worksheet on the internet with the answer below being AgSO4. That will confuse people (like me!).   I'll write to the owner of the site about it.

Point taken re using charges when referring to ions, I think you mean I should have said SO₄^2- instead of SO₄? 

I'm not sure what you mean when you say:

please refer to ions whenever you are talking about water solutions

does this relate to my question here?

Thanks Borek.

[Borek]

Point taken re using charges when referring to ions, I think you mean I should have said SO₄^2- instead of SO₄?

Exactly.

I'm not sure what you mean when you say:

please refer to ions whenever you are talking about water solutions

does this relate to my question here?

Yes - these reactions take place in water. The real question was in fact whether

Cu²⁺ + 2Ag -> Cu + 2Ag⁺

is possible. SO₄^2- is only a spectator.

[Bel-p]

Oh no, now I'm really confused.  I thought it was going to be Ag or Cu+ that would react with the SO4+, not Ag and Cu+ reacting together.  I'm not sure I knew that metals could react together...

[Borek]

In this case displacement is a reaction between metal ion and solid metal - solid becames ions, ions became solid. That's what reactivity series tells us about metals - which one will be ionic, which elemental after the reaction.

[mike]

You can still write the reaction equation, this doesn't mean the reaction will actually happen, but you can still write it.

[rctrackstar2007]

Oh no, now I'm really confused.  I thought it was going to be Ag or Cu+ that would react with the SO4+, not Ag and Cu+ reacting together.  I'm not sure I knew that metals could react together...

no, no, the two are not reacting together. the SO₄^2- is a spectator ion and does not get included in the reaction. does that make sense?

[Bel-p]

no, no, the two are not reacting together. the SO₄^2- is a spectator ion and does not get included in the reaction. does that make sense?

No, not really.

[tennis freak]

what he is trying to say (i believe) is that the SO₄^2- is not a reacting molecule and thus does not need to be in the net ionic equation which is just for the things that react together, better?

[rctrackstar2007]

no, no, the two are not reacting together. the SO₄^2- is a spectator ion and does not get included in the reaction. does that make sense?

No, not really.

the whole reaction is Ag +  CuSO4 --> Cu + Ag₂SO₄

but being that the SO₄ doesn't do anything, only the anions do something, you won't include it in your reaction

the net ionic equation would then be: Ag + Cu²⁺ --> Cu + Ag^-

make sense yet?

[mrdeadman]

Oh no, now I'm really confused.  I thought it was going to be Ag or Cu+ that would react with the SO4+, not Ag and Cu+ reacting together.  I'm not sure I knew that metals could react together...

it's an oxidation-reduction reaction. i guess you haven't learned about those yet. one metal gains electrons and one metal loses them. whichever metal is more reactive will lose electrons and will combine with the anion. the anion does not change, which is why it is left out in the overall written reaction.

[mrdeadman]

but being that the SO₄ doesn't do anything, only the anions do something, you won't include it in your reaction

i think you mean cation

[rctrackstar2007]

but being that the SO₄ doesn't do anything, only the anions do something, you won't include it in your reaction

i think you mean cation

oops, that is what i meant 

Bel-p, have you learned about redox, and do you understand this all yet?