JEE Advanced 2023 Paper 2 Q08 Chemistry Inorganic Chemistry Qualitative Analysis Medium

JEE Advanced 2023 Paper 2 · Q08 · Qualitative Analysis

$H_2S$ ($5$ moles) reacts completely with acidified aqueous potassium permanganate solution. In this reaction, the number of moles of water produced is $x$, and the number of moles of electrons involved is $y$. The value of $(x + y)$ is ___.

Reveal answer + step-by-step solution

Correct answer:18

Solution

Balanced reaction: $2KMnO_4 + 3H_2SO_4 + 5H_2S \to K_2SO_4 + 2MnSO_4 + 8H_2O + 5S$. So per $5$ mol $H_2S$, $x = 8$ mol $H_2O$ produced. Electron balance: each $H_2S \to S$ loses $2$ electrons, total $5\cdot 2 = 10$ mol $e^-$. So $y = 10$. $x + y = 18$.

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