Does the reactivity series of metals hold true for organic compounds?

[Yashbhatt]

I've learned that a more active metal displaces a less reactive one. So, according to the reactivity series Ca cannot displace Na but in he reaction given at http://en.wikipedia.org/wiki/Soap_scum
Na is displaced by Ca.
What is the reason for this exception?

 

[Adithyan]

I've learned that a more active metal displaces a less reactive one. So, according to the reactivity series Ca cannot displace Na but in he reaction given at http://en.wikipedia.org/wiki/Soap_scum
Na is displaced by Ca.

I am afraid you are wrong. ''Na'' is not replaced by Ca but Na⁺ is getting replaced by Ca⁺². The reason for this displacement reaction is given by Fajan's rule. Fajan's rule states that lesser the size of cation, more stable is the compound/ionic salt. So here, size of calcium cation is lesser than sodium cation and hence greater product stability, thus the product.

Reactivity series applies to (Metal + Other compound) kind of reactions.

Eg: Na + H₂O = NaOH + 1/2H₂

 

[Yashbhatt]

But if we have reactions like CuSO₄ + Na → Na₂SO₄ + Cu
In such reactions we have Cu in the ion form i.e. Cu₂₊. So in this reaction aren't the cations of copper displaced?

 

[Adithyan]

Yeah. But, the one displacing it, i.e sodium is in the form of metal.

 

[Borek]

But if we have reactions like CuSO₄ + Na → Na₂SO₄ + Cu
In such reactions we have Cu in the ion form i.e. Cu₂₊. So in this reaction aren't the cations of copper displaced?

This is rather bad example. Better one will be

2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag

or, in the net ionic form

2Ag⁺ + Cu → Cu²⁺ + 2Ag