Q27 / 200 · Manipal (MET) 2010 · Chemistry

When hydrogen peroxide is added to acidified potassium dichromate, a blue colour is produced due to formation of

  • A
    $\mathrm{CrO}_3$
  • B
    $\mathrm{Cr}_2 \mathrm{O}_3$
  • Correct answer
    C
    $\mathrm{CrO}_5$
  • D
    $\mathrm{CrO}_4^{2-}$

Solution

$\mathrm{H}_2 \mathrm{O}_2$ oxidises the acidified potassium dichromate solution into blue peroxide of chromium, $\mathrm{CrO}_5$. $\mathrm{Cr}_2 \mathrm{O}_7^{2-}+2 \mathrm{H}^{+}+4 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{CrO}_5+5 \mathrm{H}_2 \mathrm{O}$

Hence, the correct answer is option: 'C'.

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