# Question #57859

Mar 24, 2014

Here are the definitions I use.

#### Explanation:

Ionization is the conversion of a neutral molecule or atom to an ion.

Thus, the conversion of an $\text{Na}$ atom to ${\text{Na}}^{+}$ is an ionization.

When $\text{HCl}$ gas dissolves in water, it reacts to form separate ${\text{H"_3"O}}^{+}$ and $\text{Cl"^"-}$ ions.

$\text{HCl(g)" + "H"_2"O(l)" → "H"_3"O"^+"(aq)" + "Cl"^"-""(aq)}$

This is also a dissociation process.

Dissociation is a process in which a compound separates into two or more parts.

For example, water dissociates into hydronium and hydroxide ions.

When $\text{NaCl}$ dissolves in water, it forms separate ${\text{Na}}^{+}$ and $\text{Cl"^"-}$ ions. This is a dissociation process.

$\text{NaCl(s)" → "Na"^"+""(aq)" + "Cl"^"-""(aq)}$

Here's a great video that shows how water dissolves salt.

${\text{N"_2"O}}_{4}$ decomposes into two ${\text{NO}}_{2}$ molecules. This is a dissociation process.

${\text{O"_2"N-NO"_2 → "2NO}}_{2}$

Dissolution is the process in which the particles of a substance move into the solvent.

The process may not involve dissociation, as in the dissolving of sugar …

(from antoine.frostburg.edu)

… or it may, as in the case of sodium chloride.

Sugar does not dissociate in water, but $\text{NaCl}$ does dissociate into ions when it dissolves.