Understanding Osmolarity

* Osmolarity is a measure of the total concentration of solute particles in a solution. It's expressed in osmoles per liter (Osm/L).

* One osmole represents 6.022 x 10²³ particles (Avogadro's number) of a solute.

Calculating Osmolarity

1. Dissociation: Ammonium phosphate dissociates in solution as follows:

(NH₄)₃PO₄ → 3 NH₄⁺ + PO₄³⁻

2. Number of Ions: This means that each mole of (NH₄)₃PO₄ produces 4 moles of ions (3 moles of NH₄⁺ and 1 mole of PO₄³⁻).

3. Osmolarity Calculation:

* Molarity (M) = 0.4 M

* Number of ions per formula unit = 4

* Osmolarity = Molarity x Number of ions

* Osmolarity = 0.4 M x 4 = 1.6 Osm/L

Therefore, the osmolarity of a 0.4 M Ammonium Phosphate solution is 1.6 Osm/L.