JEE Main · 2022 · 28 Jun 2022 · Shift 2 · Redox Reactions and Electrochemistry

0.01

KMnO X_{4}

solution was added to 20.0 mL of 0.05 M Mohr's salt solution through a burette. The initial reading of 50 mL burette is zero. The volume of

KMnO X_{4}

solution left in the burette after the end point is ______ mL. (nearest integer)

Answer: 30

Solution

Using the normality equation for redox titration:

N_{1} V_{1} = N_{2} V_{2}

For

KMnO X_{4}

in acidic medium, n-factor = 5
For Mohr's salt (

FeSO X_{4} \cdot (NH X_{4}) X_{2} SO X_{4} \cdot 6 H X_{2} O

), n-factor = 1

N_{1} = 0.01 \times 5 = 0.05

N (for

KMnO X_{4}

)

N_{2} = 0.05 \times 1 = 0.05

N (for Mohr's salt)

0.05 \times V_{1} = 0.05 \times 20

V_{1} = 20

mL (volume of

KMnO X_{4}

used)

Volume left in burette =

50 - 20 = 30

JEE Main · 2022 · 28 Jun 2022 · Shift 2 · Integer answer