Question

The number of moles of $K_{2}C{r}_2{O}_7$ that will be needed to react with one mole of $H_{2}S$ in acidic medium is :

• A. $\frac{1}{6}$
• B. $\frac{1}{3}$
• C. $\frac{2}{5}$
• D. $\frac{2}{3}$

Answer 1

Answer: (B)

$\frac{1}{3}$

The balanced chemical equation for the reaction between potassium dichromate and hydrogen sulphide is as given below:

$K_{2}C{r}_2{O}_7+4H_{2}S{O}_4+3H_{2}S\to K_{2}S{O}_4+C{r}_2(S{O}_4{)}_3+7H_{2}O+3S$

$1$ mol of potassium dichromate reacts with $3$ moles of hydrogen sulphide.

Hence, the number of moles of $K_{2}C{r}_2{O}_7$ that will be needed to react one mole of $H_{2}S$ in acidic medium is $\frac{1}{3}$.

Option B is correct.