Question

$K_{2}C{r}_2{O}_7+conc.H_{2}S{O}_4+H_2{O}_2+ether⟶$ blue perchromic anhydride (in ethereal layer)
Blue color is due to :

• A. $Cr{O}_3$
• B. $H_{2}Cr{O}_4$
• C. $H_{2}C{r}_2{O}_3$
• D. $Cr{O}_5$

Answer 1

The correct option is D $Cr{O}_5$

$C{r}_2{O}_7^{2-}+2O{H}^{-}\to 2Cr{O}_4^{2-}+H_{2}O$

If an acidic solution of a chromate is treated with $H_2{O}_2$ in the presence of ether / amyl alcohol, a deep-blue solution of chromium pentoxide or chromic peroxide is obtained in ethereal layer.

$Cr{O}_4^{2-}+2H^{+}2H_2{O}_2\to Cr{O}_5+3H_{2}O$

Deep blue

colouration