Acidified KMnO4 oxidises Cu2S to Cu^2+ and SO2 (the manganese ends as Mn^2+). The number of moles of KMnO4 consumed per mole of Cu2S is:

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Acidified $KMnO X_{4}$ oxidises $Cu X_{2} S$ to $Cu X^{2 +}$ and $SO X_{2}$ (the manganese ends as $Mn X^{2 +}$ ). The number of moles of $KMnO X_{4}$ consumed per mole of $Cu X_{2} S$ is:

Cu:

+ 1 \to + 2

for 2 atoms gives 2 electrons; S:

- 2 \to + 4

gives 6 electrons. n-factor of

Cu X_{2} S

= 8

. Each

KMnO X_{4}

accepts 5 electrons, so moles of

KMnO X_{4}

per mole

Cu X_{2} S

= 8/5 = 1.6