Verified Solution • 2025–26 Session moderate

QJEEM22Ch7dc3: JEE Main 2022 Chemistry - Class 11 JEEM22Ch7dc3 Solution: of hypo solution is used for the titration of of copper…

20 mL20 \mathrm{~mL} of 0.02 M0.02\, \mathrm{M} hypo solution is used for the titration of 10 mL10 \mathrm{~mL} of copper sulphate solution, in the presence of excess of KI using starch as an indicator. The molarity of Cu2+\mathrm{Cu}^{2+} is found to be ____________ ×10−2 M\times 10^{-2} \,\mathrm{M} . [nearest integer]

Given : 2 Cu2++4 I−→Cu2I2+I22 \,\mathrm{Cu}^{2+}+4 \,\mathrm{I}^{-} \rightarrow \mathrm{Cu}_{2} \mathrm{I}_{2}+\mathrm{I}_{2}

I2+2 S2O32−→2I−+S4O62−\mathrm{I}_{2}+2 \mathrm{~S}_{2} \mathrm{O}_{3}^{2-} \rightarrow 2 \mathrm{I}^{-}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}

Step-by-Step Verified Solution

2Cu2++4I−→Cu2l2+I22 \mathrm{Cu}^{2+}+4 \mathrm{I}^{-} \rightarrow \mathrm{Cu}_{2} \mathrm{l}_{2}+\mathrm{I}_{2}

I2+S2O32−→2I−+S4O62−\mathrm{I}_{2}+\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \rightarrow 2 \mathrm{I}^{-}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}

Milliequivalents of hypo solution =0.02×20=0.4=0.02 \times 20=0.4

Milliequivalents of Cu2+\mathrm{Cu}^{2+} in 10 mL10 \mathrm{~mL} solution =

Milliequivalents of I2=\mathrm{I}_{2}= Milliequivalents of hypo = 0.4

Millimoles of Cu2+\mathrm{Cu}^{2+} ions in 10 mL=0.410 \mathrm{~mL}=0.4

Molarity of Cu2+\mathrm{Cu}^{2+} ions =0.410=0.04 M=\frac{0.4}{10}=0.04 \,\mathrm{M}

=4×10−2 M=4 \times 10^{-2} \,\mathrm{M}

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring