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# 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

$(a)\;3 \\ (b)\;4 \\(c)\;5 \\(d)\;6$
Can you answer this question?

In the redox reaction, $Cr_2O_7^{2-}$ oxidises Mohr's salt, $FeSO_4.(NH_4)_2SO_4.6H_2O$
$6Fe^{2+}+Cr_2O_7^{2-} +14 H^{+} \longrightarrow 6Fe^{3+} +2Cr^3+7H_2O$
Mohr's salt $[FeSO_4.(NH_4)_2SO_4.6H_2O]$ and
dichromate reacts in $6:1$ molar ratio . or one more of $Cr_2O_7^{2-}$ will require six moles of $Fe^{2+}$ ions
Hence d is the correct answer.
answered Mar 21, 2014 by