Question

The equation between an acid and a base is
XOH + HY → XY+H2O
which of the following is the cation part of
salt?
(b) OH
(c) H
(d) Y
(a) x

Please give a brief explanation of the answer!
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Answer 1

a) X is the cation of salt.

Answer 2

Strictly speaking, there were no molecules, unless the acid was in gaseous form. Let me explain,

We know the products are NaCl and H2O. NaCl exists in solution as Na+ and Cl-. The former must come from a base containing Na+, and that must be NaOH. But NaOH doesn’t exist as molecules, it exists as Na+ and OH- even in the solid phase, as well as in aqueous solution. (The other bases containing Na+, Na2CO3 and NaHCO3, would produce carbon dioxide as well among the products. I suppose the base could be Na2O, but it’s not as likely, and Na2O is also an ionic compound.)

As for Cl-, the only acid that will produce Cl- ions and nothing else is HCl. Hydrochloric acid, the solution of HCl in water, exists as H+ and Cl- ions, so again no molecules are involved. Pure HCl is a gas, however, and it does consist of molecules, so in this case there was a molecule (but not two different molecules).

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If this is homework, just write “NaOH” and “HCl”. I’m sure that’s what the teacher wants.