Hydrogen And Its Compounds Question 30
Question: An orange coloured solution acidified with $ H_2SO_4 $ and treated with a substance ‘X’ gives a blue coloured solution of $ CrO_5 $ . The substance ‘X’ is
Options:
A) $ H_2O_2 $
B) $ H_2O $
C) dil $ HCl $
D) conc $ HCl $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] $ K_2Cr_2O_7 $ an orange coloured solution, on acidification with dil $ H_2SO_4 $ is oxidised by $ H_2O_2 $ to blue peroxide of chromium, $ CrO_5 $ which is unstable. $ \begin{align} & K_2Cr_2O_7+H_2SO_4\to K_2SO_4+H_2Cr_2O_7 \\ & [ H_2O_2\to H_2O+[O] ]\times 4 \\ & H_2Cr_2O_7+4[O]\to 2CrO_5+H_2O \\ & \overline{\underline{K_2Cr_2O_7+H_2SO_4+4H_2O_2\to 2CrO_5+K_2SO_4+5H_2O}} \\ \end{align} $
BETA
