8.15     Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with:

                (iii)\; H_{2}S

Answers (1)
M manish

Potassium dichromate oxidise H_{2}S (hydrogen sulphide ) to sulphur (zero oxidation state)
The oxidising action of dichromate ion is -
\\Cr_{2}O_{7}^{2-}+14H^{+}+6e^{-}\rightarrow 2Cr^{3+}+7H_{2}O\\ H_{2}S\rightarrow S + 2H^{+}+2e^{-}]\times 3
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Cr_{2}O_{7}^{2-}+14H^{+}+3H_{2}S\rightarrow 2Cr^{3+}+3S+7H_{2}O

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