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JEE Main 20179 AprilOnline
Exam
JEE Main
Year
2017
Date
9 April
Mode
Online
Subject
Chemistry
Chapter
Ionic Equilibrium

JEE Main 2017 · 9 April · Online · Chemistry · Ionic Equilibrium

50mL of 0 .2 M ammonia solution is treated with 25mLof0 . 2MHCl ....

50mL50mL of 0.2M0 .2 M ammonia solution is treated with 25mLof0.2MHCl25mLof0 . 2MHCl. If pKb{pK}_{b} of ammonia solution is 4.754 . 75, the pHpH of the mixture will be:

Options

  1. A8.258 . 25
  2. B9.259 . 25
  3. C3.753 . 75
  4. D4.754 . 75

Correct answer

B. 9.259 . 25

Step-by-step solution

NH3+HCl⇌NH4Clmolesatt=050×.2×10−325×.2×10−3−molesatt=t25×.2×10−3025×.2×10−3\begin{array}{ll}{NH}_{3} + HCl ⇌ {NH}_{4}Cl \\ molesat\text{}t = 050 \times . 2 \times {10}^{- 3}25 \times . 2 \times {10}^{- 3} - \\ molesat\text{}t = t25 \times . 2 \times {10}^{- 3}025 \times . 2 \times {10}^{- 3}\end{array}

∴salt and basepresentinsoluton,soitisbasicBuffersolution.∴ salt \text{ and } basepresentinsoluton, soitisbasicBuffersolution .

pOH=pkb(NH3)+logsaltbase=4.75pOH = pkb\left({NH}_{3}\right) + log \dfrac{salt}{base} = 4 .75∴pOH=Pkb=4.75∴ pOH = Pkb = 4 .75

pH=14−pOH=14−4.75=9.25.pH = 14 - pOH = 14 - 4 . 75 = 9 . 25 .

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