MCQ
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
    $5$
  • $6$

Answer

Correct option: D.
$6$
d
The formula of Mohr's salt is $F eSO { }_4\left( NH _4\right)_2 SO _4$. It is a mixture of ferrous sulfate and ammonium sulfate. Ferrous sulfate is oxidized by potassium dichromate.

The reaction is as follows:

$K _2 Cr _2 O _7+6 F eSO _4+7 H _2 SO _4 \rightarrow K _2 SO _4+ Cr _2\left( SO _4\right)_3+3 Fe _2\left( SO _4\right)_3+7 H _2 O$

$1$ mole of potassium dichromate reacts with 6 moles of ferrous sulphate. Thus, the number of moles of Mohr's salt required per mole of dichromate is $6.$

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