Question

The compound which is responsible for the green colour formed when $S{O}_2$ is bubbled through acidified potassium dichromate solution is:

• A. Nitroso iron $\left[II\right]$ sulphate
• B. Iron $\left[III\right]$ chloride
• C. Chromium sulphate
• D. Lead $\left[II\right]$ chloride

Answer 1

Answer: (C)

Chromium sulphate

If sulfur dioxide gas is bubbled through acidified potassium dichromate solution, the orange solution turns green, indicating that $C{r}_2{O}_7^2$ has been reduced to $C{r}^{3+}$.
$C{r}_2{O}_7^2+2H^{+}+3S{O}_2\to 2C{r}^{3+}+H_{2}O+3S{O}_4^2$