Respuesta :
Answer : The pH of the solution is, 4.2
Explanation : Given,
[tex]K_a=1.8\times 10^{-5}[/tex]
Concentration of [tex]CH_3CO_2H[/tex] = 0.10 M
Concentration of [tex]CH_3CO_2K[/tex] = 0.030 M
First we have to calculate the value of [tex]pK_a[/tex].
The expression used for the calculation of [tex]pK_a[/tex] is,
[tex]pK_a=-\log (K_a)[/tex]
Now put the value of [tex]K_a[/tex] in this expression, we get:
[tex]pK_a=-\log (1.8\times 10^{-5})[/tex]
[tex]pK_a=5-\log (1.8)[/tex]
[tex]pK_a=4.7[/tex]
Now we have to calculate the pH of buffer.
Using Henderson Hesselbach equation :
[tex]pH=pK_a+\log \frac{[Salt]}{[Acid]}[/tex]
[tex]pH=pK_a+\log \frac{[CH_3CO_2K]}{[CH_3CO_2H]}[/tex]
Now put all the given values in this expression, we get:
[tex]pH=4.7+\log (\frac{0.030}{0.10})[/tex]
[tex]pH=4.2[/tex]
Therefore, the pH of the solution is, 4.2
