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JEE Main 201323 AprilOnline
Exam
JEE Main
Year
2013
Date
23 April
Mode
Online
Subject
Chemistry
Chapter
Ionic Equilibrium

JEE Main 2013 · 23 April · Online · Chemistry · Ionic Equilibrium

What is the pH of a 10^ -4 M OH^ - solution at 330 ~K , if K_ w at...

What is the pH\mathrm{pH} of a 10−4MOH−10^{-4} \mathrm{M} \mathrm{OH}^{-}solution at 330 K330 \mathrm{~K}, if Kw\mathrm{K}_{\mathrm{w}} at 330 K330 \mathrm{~K} is 10−13.610^{-13.6} ?

Options

  1. A4
  2. B9.09.0
  3. C10
  4. D9.69.6

Correct answer

D. 9.69.6

Step-by-step solution

Given at 330K330 \mathrm{ K}Kw=10−13.6 i.e. pKw=pH+pOH∵pOH2=−log⁡[OH−]13.6=pH+pOHpOH=−log⁡10−413.6=pH+4∴pH=13.6−4=9.6\begin{aligned} \mathrm{K}_w & =10^{-13.6} \\ \text{ i.e. } \quad \mathrm{pK}_w & =\mathrm{pH}+\mathrm{pOH} \\ \because \quad \mathrm{pOH}^2 & =-\log \left[\mathrm{OH}^{-}\right] \\ 13.6 & =\mathrm{pH}+\mathrm{pOH} \\ \mathrm{pOH} & =-\log 10^{-4} \\ 13.6 & =\mathrm{pH}+4 \\ \therefore \quad \mathrm{pH} & =13.6-4 \\ & =9.6 \end{aligned}
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