When $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ is converted into $\mathrm{K}_2 \mathrm{CrO}_4$, the

Question

When $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ is converted into $\mathrm{K}_2 \mathrm{CrO}_4$, the change in oxidation number of chromium is

Professor PC Thomas Classes · Answer

(a) : Let the oxidation state of Cr in $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7=x$\ $ (+1 	imes 2)+2 x+(-2 	imes 7)=0 $ or $\quad+2+2 x-14=0 \Rightarrow x=+6$ Let the oxidation state of Cr in $\mathrm{K}_2 \mathrm{CrO}_4=x$\ $ \begin{aligned} & (+1 	imes 2)+x+(-2 	imes 4)=0 \ & 2+x-8=0 \quad \Rightarrow \quad x=+6 \end{aligned} $\ $	herefore \quad$ Change in oxidation state of Cr is zero when it changes from $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ to $\mathrm{K}_2 \mathrm{CrO}_4$.