[cliverlong]

Hi,

1.
   I was asked "how do I know a chemical is a salt?". I replied "a salt is formed by the reaction of an acid with a base". The reply to my reply was "OK, but if I am given a compound such as copper(II)sulphate or ammonium hydroxide or copper oxide or magnesium oxide or whatever, can I apply a general rule to determine which are salts and which are not?"

   That left me a bit stumped because I thought one would have to think up a suitable acid-base pairing to create the salt. And what if I can't think of a pairing but it does exist?

2.

NaHSO₄ is an acidic salt because it can donate protons in solution. Correct?

3.

Although CaCO₃ is insoluble in water, if we add acid say hydrochloric, then because carbon dioxide and water are generated and calcium chloride is formed in solution, and calcium chloride is a salt (ha, ha!) then we can say CaCO₃ is a basic salt. Is this right??


Ta, Clive

[Rabn]

1)  I would call any highly soluble substance that releases a metal ion upon dissociation a salt.  The keys words being highly soluble, dissociates and metal ion.

2)  Are you familiar with equilibrium? If you are, take a look at the 2 Ka values for H2SO4.  Maybe do a quick calculation using an I.C.E. table.

3)  Again, take a look at the Ka of carbonic acid, maybe another quick calculation here would as well.

Just assume 1 molar solutions to keep the calc.s easy 

[cliverlong]

1)  I would call any highly soluble substance that releases a metal ion upon dissociation a salt.  The keys words being highly soluble, dissociates and metal ion.

I thought that. Then I thought
"what about ammonium chloride?"

Explicitly. Is that a salt? Where's the metal?


Ta

Clive

[Borek]

What about NaOH?

Could be your general rule can be falsified (phew, I am more then sure it can be falsified, we are talking about chemistry), but for ammonium hydroxie, MgO and CuO - are they products of reaction between acid and base? No. Are they salts? No. Is copper (II) sulfate product of such a reaction? Yes. Is it a salt? Yes.

[virus_freak]

2) Na2HSO4 is an acid salt because not all of the H+ has been liberated from the Acid