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The instantaneous rate of disappearance of MnO4− ion in the following reaction is 4.56 × 10−3 Ms−1 2MnO4− + 10I− + 16H+ → 2Mn2+ + 5I2 + 8H2O The rate of appearance of I2 is :

1. 4.56 × 10−4 Ms−1
2. 1.14 × 10−2 Ms−1
3. 1.14 × 10−3 Ms−1
4. 5.7 × 10−3 Ms−1

Correct answer: 1.14 × 10−2 Ms−1

Solution

The stoichiometry of the reaction shows that for every 2 moles of MnO4− that disappear, 5 moles of I2 are produced. Therefore, the rate of appearance of I2 is calculated by multiplying the rate of disappearance of MnO4− by the ratio of I2 to MnO4−, which is 5/2, resulting in a rate of 1.14 × 10−2 Ms−1.

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