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

### Relationship between pH values and molarities of acids or alkalis.

• 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.