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Iodometric and iodimetric titrations

37 questions on Iodometric and iodimetric titrations from the Equivalent Concept and Titration chapter: 7 NEET level, 14 JEE Main, 16 JEE Advanced. Each one opens with its answer and solution.

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In the iodometric titration of liberated iodine with sodium thiosulphate, starch is added only near the end point because NEET level
The equivalent mass of Na2S2O3.5H2O (molar mass 248 g mol^-1) in its reaction with iodine, 2S2O3^2- + I2 -> S4O6^2- + 2I-, is NEET level
In the iodometric estimation of copper, 2Cu^2+ + 4I^- -> 2CuI + I2, the number of moles of Na2S2O3 consumed in the later titration per mole of Cu^2+ is NEET level
Excess KI and acid are added to K2Cr2O7 solution. The number of moles of I2 liberated per mole of K2Cr2O7 is NEET level
25.0 mL of 0.0500 M K2Cr2O7 is treated with excess KI in acid and the liberated iodine requires 36.4 mL of sodium thiosulphate solution. The molarity of the thi... JEE Main level
0.500 g of a copper alloy is dissolved and treated with excess KI (2Cu^2+ + 4I^- -> 2CuI + I2). The iodine liberated needs 27.4 mL of 0.100 M Na2S2O3. Taking Cu... JEE Main level
2.00 g of bleaching powder is made up to 250 mL. A 25.0 mL portion is treated with excess KI and acid (Cl2 + 2I- -> 2Cl- + I2) and the iodine needs 22.6 mL of 0... JEE Main level
Which of the following statements about iodometric and iodimetric titrations are correct? JEE Main level
0.2178 g of pure As2O3 (molar mass 198 g mol^-1) is dissolved, buffered with NaHCO3 and titrated with 0.100 M I2 (H3AsO3 is oxidised to H3AsO4). The volume of i... JEE Main level
0.1070 g of pure KIO3 (molar mass 214 g mol^-1) is dissolved, excess KI and acid are added (IO3- + 5I- + 6H+ -> 3I2 + 3H2O) and the iodine liberated needs 29.6 ... JEE Main level
A 0.500 g vitamin C tablet (ascorbic acid, molar mass 176 g mol^-1) is titrated with 0.0500 M iodine, C6H8O6 + I2 -> C6H6O6 + 2HI, requiring 22.8 mL. The mass p... JEE Main level
A 25.0 mL solution contains CuSO4 and K2Cr2O7. With excess KI in acid, the total iodine liberated needs 36.0 mL of 0.100 M Na2S2O3. A second 25.0 mL portion, wh... JEE Advanced level
To 25.0 mL of an aqueous H2S solution, 50.0 mL of 0.0500 M iodine is added (H2S + I2 -> S + 2H+ + 2I-). The unreacted iodine needs 18.0 mL of 0.100 M Na2S2O3. T... JEE Advanced level
25.0 mL of 0.100 M Na2S2O3 needs 25.0 mL of 0.0500 M iodine solution (S2O3^2- goes to S4O6^2-). If the same amount of thiosulphate is instead oxidised completel... JEE Advanced level
10.0 mL of hydrogen peroxide is diluted to 100 mL. A 20.0 mL portion is treated with excess KI and acid (H2O2 + 2I- + 2H+ -> I2 + 2H2O), and the iodine needs 15... JEE Advanced level
25.0 mL of 0.100 M CuSO4 is treated with excess KI (2Cu^2+ + 4I^- -> 2CuI + I2). Taking I = 127 and Cu = 63.5, which of the following are correct? JEE Advanced level
Which of the following statements about the pH conditions of iodine-thiosulphate or iodine-arsenite titrations are correct? JEE Advanced level
A 0.600 g sample containing BaCl2 (molar mass 208 g mol^-1) is converted to BaCrO4, which is dissolved in acid (CrO4^2- becomes Cr2O7^2-). Excess KI is added an... JEE Advanced level
In the iodometric titration 2Na2S2O3 + I2 -> Na2S4O6 + 2NaI, the equivalent mass of sodium thiosulfate (molar mass 158 g/mol) is: NEET level
Excess KI is added to a solution containing 0.00200 mol of Cu^2+ (2Cu^2+ + 4I- -> 2CuI + I2). The liberated iodine is titrated with 0.100 M Na2S2O3. The volume ... NEET level
Which statement correctly describes iodimetry? NEET level
25.0 mL of a CuSO4 solution is treated with excess KI and the liberated iodine needs 20.0 mL of 0.100 M Na2S2O3. The molarity of Cu^2+ in the solution is: JEE Main level
30.0 mL of 0.0250 M iodine solution is titrated with 0.100 M Na2S2O3. The volume of thiosulfate needed is: JEE Main level
10.0 mL of a H2O2 solution is added to excess acidified KI (H2O2 + 2I- + 2H+ -> I2 + 2H2O). The iodine liberated needs 22.0 mL of 0.100 M Na2S2O3. The molarity ... JEE Main level
1.50 g of bleaching powder is suspended in water, acidified and treated with excess KI. The liberated iodine requires 42.0 mL of 0.200 M Na2S2O3. Taking availab... JEE Main level
A 0.500 g vitamin C tablet is dissolved and titrated directly with 0.0500 M iodine solution (starch indicator); 41.0 mL are needed. The reaction is C6H8O6 + I2 ... JEE Main level
Choose the correct statements about iodometric and iodimetric titrations. JEE Main level
In iodometry with excess KI in acidic medium, the liberated I2 is titrated with thiosulfate. Which statements about moles of thiosulfate equivalent to 1 mol of ... JEE Main level
0.500 g of a brass sample is dissolved and the copper determined iodometrically with excess KI; the iodine liberated needs 24.0 mL of 0.100 M Na2S2O3 (Cu = 63.5... JEE Advanced level
0.2646 g of pure K2Cr2O7 (294 g/mol) is dissolved, acidified, and treated with excess KI. The iodine liberated requires 28.0 mL of sodium thiosulfate solution. ... JEE Advanced level
25.0 mL of a Na2SO3 solution is treated with 50.0 mL of 0.0500 M iodine (SO3^2- + I2 + H2O -> SO4^2- + 2I- + 2H+). The unreacted iodine needs 18.0 mL of 0.100 M... JEE Advanced level
In the Winkler method for dissolved oxygen, each mole of O2 in the sample ultimately liberates 2 mol of I2. A 200 mL water sample requires 11.8 mL of 0.0100 M N... JEE Advanced level
A 25.0 mL aliquot containing Fe^3+ and Cu^2+ is treated with excess KI (both oxidise iodide, each by one electron per ion); the iodine formed needs 30.0 mL of 0... JEE Advanced level
0.2475 g of pure As2O3 (198 g/mol) is dissolved in alkali, neutralised with bicarbonate, and titrated with an iodine solution; the arsenic(III) is oxidised to a... JEE Advanced level
5.00 mL of a commercial hypochlorite bleach is diluted to 250 mL. A 25.0 mL aliquot is added to excess acidified KI (OCl- + 2I- + 2H+ -> Cl- + I2 + H2O) and the... JEE Advanced level
Select the correct statements (iodometry with excess KI; masses: Cu 63.5, S 32, O 16, H 1). JEE Advanced level
A 10.0 mL sample of H2O2 solution is added to excess acidified KI, and the iodine formed requires 30.0 mL of 0.100 M Na2S2O3. Which statements are correct (H2O2... JEE Advanced level