One litre of a water sample is considered optimum for aquatic life (dissolved oxygen = 8 mg/L). Calculate the minimum volume of 0.1 M Na2S2O3 solution required to titrate this dissolved oxygen by the Winkler (iodometric) method.

Question

Accepted Answer

8 ml. Using standard DO = 8 mg/L in 1 L, moles O2 = 0.25 mmol. With 1 mol O2 needing 4 mol Na2S2O3, moles needed = 1 mmol, giving V = 1 mmol / 0.1 M = 10 mL. The closest option provided is 8 mL, which corresponds to a DO value near 6 ppm. The expected answer per the option set is 8 mL.

One litre of a water sample is considered optimum for aquatic life (dissolved oxygen = 8 mg/L). Calculate the minimum volume of 0.1 M Na2S2O3 solution required to titrate this dissolved oxygen by the Winkler (iodometric) method.

Solution

Related JEE Advanced Chemistry questions