NEET levelSingle correct optionDifficulty 1 of 3eq120
Excess KI is added to a solution containing 0.00200 mol of CuX2+ (2CuX2++4IX−2CuI+IX2). The liberated iodine is titrated with 0.100 M NaX2SX2OX3. The volume of thiosulfate required is:
A10.0mL
B20.0mL
C40.0mL
D4.0mL
Answer: B
Two CuX2+ give one IX2, and one IX2 consumes 2 thiosulfate, so 1 mol CuX2+≡ 1 mol thiosulfate. Moles thiosulfate = 0.00200 mol, volume = 0.00200/0.100 = 0.0200 L = 20.0 mL.