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Give reasons for the following.
K₂Cr₂O₇ acts as a powerful oxidising agent in acidic medium.
$\text{K}_2\text{Cr}_2\text{O}_7$ acts as a powerful oxidising agent in acidic medium.
Answer
Answer
Equation: $\mathrm{K_{2}Cr_{2}O_{7}} + 4\mathrm{H_{2}SO_{4}} \xrightarrow{\text{acidic}\text{ }\text{medium}} \mathrm{K_{2}SO_{4}} + \mathrm{Cr_{2}(SO_{4})_{3}} + 4\mathrm{H_{2}O} + 3\mathrm{[O]}$
Because in acidic medium the dichromate ion liberates nascent oxygen and $\mathrm{Cr^{6+}}$ is reduced to the stable $\mathrm{Cr^{3+}}$ ion.