Question

How do you write an equation showing how HCl, which is a molecular substance and strong acid, could give ions when added to water?

Answer 1

`HCl(g) + H_2O(l) rarr H_3O^+ + Cl^(-)`

Explanation:

As you say, hydrogen chloride is a room temperature gas; however, it is mighty soluble in water. And in water we conceive that it protonates the water molecular to give `H_3O^+`. `HCl` PROTONATES the water solvent to form water-solvated hydronium ions and chloride ions......

`H_3O^+`, the so-called hydronium ion, is our conception of a protonated water molecule. So far as anybody knows, it is a cluster of 2-4 water molecules with AN EXTRA `H^+` incorporated in the cluster, i.e. `H_5O_2^+` or `H_7O_3^+`. We call it `H_3O^+` or even `H^+` for convenience. The extra proton can rapidly move, or even tunnel if you like, from cluster to cluster.....