Question

What is the formula for hydrochloric acid? What are the symbols with oxidation numbers?

Answer 1

Gaseous hydrogen chloride is represented as `HCl(g)`......

Explanation:

In water, hydrogen chloride dissolves and ionizes to form aqueous hydrogen chloride:

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

Oxidation number results from distribution of the charge to the most electronegative atom; here, we get `H(+I)` and `Cl(-I)`.

Undergraduate treatment:

When we write `H_3O^+`, the `"hydronium ion"`, this is more of a convenience than an actual entity. When we write `H^+` or `H_3O^+` we mean the `"acidium"` species in water, a cluster or 3 or 4 water molecules WITH an EXTRA `H^+`, i.e. `H_7O_3^+` or `H_9O_4^+`. The extra proton rapidly exhanges between clusters, and `H_3O^+` is a convenient representation.