Which acid among the following has the highest $\mathrm{p} K_a$ value?

Which acid among the following has the highest $\mathrm{p} K_a$ value?
  1. $\mathrm{HCl}$
  2. $\mathrm{HF}$
  3. \(\mathrm{HI}\)
  4. \(\mathrm{HBr}\)

Solution

\(\mathrm{HF}\left(\mathrm{p} K_a=3.1\right)\) \(\begin{aligned} \operatorname{HCl}\left(\mathrm{p} K_a\right. & =-6.0) \\ \operatorname{HBr}\left(\mathrm{p} K_a\right. & =-9.0) \\ \operatorname{HI}\left(\mathrm{p} K_a\right. & =-9.5) . \end{aligned}\) Therefore, HF has highest \(\mathrm{p} K_a\) value. Hence, the correct option is (b).

Asked in: AP EAMCET 2020 (21 Sep Shift 1)

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