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:

Explanation

The following reaction occurs :
`6Fe^(2+) + Cr_(2)O_(7)^(2-) + 14H^(+) rarr 6 Fe^(3+) + 2 Cr^(3+) + 7H_(2)O`
From the above equation, we find that Mohr's salt `(FeSO_(4).(NH_(4))_(2)SO_(4).6H_(2)O)` and dichromate reacts in 6:1 molar ratio.