20 mL of 0.02 M hypo solution is used for the titration of 10 mL of copper sulphate solution, in the — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

# Solution **Step 1: Identify the overall reaction** From the given equations, hypo (S₂O₃²⁻) reacts with I₂ produced from Cu²⁺ and KI: - Cu²⁺ + I⁻ → CuI + I₂ - I₂ + 2S₂O₃²⁻ → 2I⁻ + S₄O₆²⁻ **Step 2: Determine the mole ratio** From the equations: - 2 Cu²⁺ produces 1 I₂ - 1 I₂ reacts with 2 S₂O₃²⁻ Therefore: **2 Cu²⁺ : 2 S₂O₃²⁻** or **1 Cu²⁺ : 1 S₂O₃²⁻** **Step 3: Calculate moles of hypo used** Moles of S₂O₃²⁻ = Molarity × Volume = 0.02 M × 20 mL = 0.4 mmol **Step 4: Calculate moles of Cu²⁺** Using 1:1 ratio: Moles of Cu²⁺ = 0.4 mmol **Step 5: Calculate molarity of Cu²⁺** Molarity = moles/Volume = 0.4 mmol / 10 mL = 0.04 M = **4.00 × 10⁻² M** Therefore, the answer is 4.00.