Concentration of Aqueous Solutions

6.5

Concentration of Aqueous Solutions

Concentration and molarity are measurements of the amount of solute that dissolves in a solvent.
The concentration can be measured in two terms, \(\text{mol dm}^{-3}\) or \(\text{g dm}^{-3}\)

The formula for concentration in \(\textbf{g dm}^{-3}\)

\(\text{Concentration } \text{(g dm}^{-3}) = \dfrac{\text{Mass of solute dissolved (g)}}{\text{Volume of solution (dm}^3)}\)

The formula for concentration in \(\textbf{mol dm}^{-3}\)

\(\text{Concentration } \text{(mol dm}^{-3}) = \dfrac{\text{Number of moles of solute (mol)}}{\text{Volume of solution (dm}^3)}\)

pH value of an acidic or an alkali depends on two factors;
- Degree of dissociation
- Molarity or concentration
Even at the same concentration, the pH value still depends on the degree of dissociation:
- Higher the degree of dissociation of an acid, the lower the pH value.
- Higher the degree of dissociation of an alkali, the higher the pH value.
Both acid and alkali depend on their pH value for molarity.
- High molarity of acid, lower the pH value.
- Higher molarity of alkali, higher the pH value.