Some Basic Concepts of Chemistry 2 Question 12
12. Consider a titration of potassium dichromate solution with acidified Mohr’s salt solution using diphenylamine as indicator. The number of moles of Mohr’s salt required per mole of dichromate is
(2007, 3M)
(a) 3
(b) 4
(c) 5
(d) 6
Show Answer
Solution:
- $n$-factor of dichromate is 6 .
Also, $n$-factor of Mohr’s salt is 1 as :
$$ \mathrm{FeSO}{4}\left(\mathrm{NH}{4}\right){2} \mathrm{SO}{4} \cdot 6 \mathrm{H}_{2} \mathrm{O} \xrightarrow{\text { O.A }} \mathrm{Fe}^{3+} $$
Mohr’s salt
$\because 1$ mole of dichromate $=6$ equivalent of dichromate.
$\therefore 6$ equivalent of Mohr’s salt would be required.
Since, $n$-factor of Mohr’s salt is 1,6 equivalent of it would also be equal to 6 moles.
Hence, 1 mole of dichromate will oxidise 6 moles of Mohr’s salt.
