Question

$C{O}_2$ and $S{O}_2$ both turns lime water milky. How will you detect the presence if both are present in a mixture?

• A. using acidified $K_{2}C{r}_2{O}_7$
• B. using basic $K_{2}C{r}_2{O}_7$
• C. using neutral $K_{2}C{r}_2{O}_7$
• D. using basic $KMn{O}_4$
  
• E. None of these
  

Answer 1

The correct option is A using acidified $K_{2}C{r}_2{O}_7$

The mixture of carbon dioxide and sulphur dioxide is passed into acidified potassium dichromate solution. Sulphur dioxide reacts with acidified potassium dichromate solution to form green coloured solution. Potassium dichromate is reduced to chromic sulphate. When carbon reacts with potassium the solution turns reddish pink.Carbon dioxide is not affected by potassium dichromate. Hence, it turns lime water milky.

$K_{2}C{r}_2{O}_7+3S{O}_2+H_{2}S{O}_4\to K_{2}S{O}_4+C{r}_2(S{O}_4{)}_3+H_{2}O$