Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10⁻³ g of K₂SO₄ in 2 L of water at 25 °C, assuming that it is completely dissociated. (T = 0.0821 L atm K⁻¹ mol⁻¹, Molar mass of K₂SO₄ = 174 g mol⁻¹)

Given, that mass of K₂SO₄, w = 25 mg = 0.025 g
Volume V = 2 L
T = 25 + 273 = 298 K
The reaction of dissociation of K₂SO₄ is,
K₂SO₄ → 2K⁺ + SO₄²⁻
Number of ions produced = 3 = van't Hoff factor
Hence, π = iCRT
⇒ π = 3 × (0.025/174) × 0.5 × 0.0821 × 298 = 5.27 × 10⁻⁵ atm