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Question: Answered & Verified by Expert
If the $\mathrm{p} K_a$ of acetic acid and $\mathrm{p} K_b$ of dimethylamine are 4.76 and 3.26 respectively, the $\mathrm{pH}$ of dimethyl ammonium acetate solution is
ChemistryIonic EquilibriumAP EAMCETAP EAMCET 2018 (22 Apr Shift 1)
Options:
  • A 7.75
  • B 6.75
  • C 7.0
  • D 8.5
Solution:
1425 Upvotes Verified Answer
The correct answer is: 7.75
$\begin{aligned} & \text { } \begin{aligned} \mathrm{pH}= & 7+\frac{1}{2}\left[\mathrm{p} K_a-\mathrm{p} K_b\right] \\ \text { Here, } \mathrm{p}_a & =4.76, \mathrm{p} K_b=3.26 \\ & =7+\frac{1}{2}[4.76-3.26] \\ & =7+\frac{1}{2}[1.50] \\ & =7+0.75=7.75\end{aligned}\end{aligned}$

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