Medium INTEGER +4 / -1 PYQ · JEE Mains 2021

When 10 mL of an aqueous solution of Fe2+ ions was titrated in the presence of dil H2SO4 using diphenylamine indicator, 15 mL of 0.02 M solution of K2Cr2O7 was required to get the end point. The molarity of the solution containing Fe2+ ions is x $\times$ 10$-$2 M. The value of x is __________. (Nearest integer)

Answer (integer) 18

Solution

milli-equivalents of Fe<sup>2+</sup> = milli-equivalents of K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub><br><br>M $\times$ 10 $\times$ 1 = 0.02 $\times$ 15 $\times$ 6<br><br>$\Rightarrow$ M = 0.18 = 18 $\times$ 10<sup>$-$2</sup> M

About this question

Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept

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