Answer : The pH of buffer is, 5.17
Explanation : Given,
[tex]pK_a=4.75[/tex]
Concentration of acetic acid = 1.00 M
Concentration of sodium acetate = 1.00 M
Volume of solution = 1.00 L
As, [tex]Moles=Concentration\times Volume[/tex]
So,
Moles of acetic acid = 1.00 mol
Moles of sodium acetate = 1.00 mol
Moles of NaOH added = 0.450 mol
The balanced chemical equilibrium reaction is:
[tex]CH_3COO+NaOH\rightleftharpoons CH_3COONa+H_2O[/tex]
Initial mole 1 0.450 1
At eqm. (1-0.450) 0 (1+0.450)
= 0.55 =1.450
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_3COONa]}{[CH_3COOH]}[/tex]
Now put all the given values in this expression, we get:
[tex]pH=4.75+\log (\frac{1.450}{0.55})[/tex]
[tex]pH=5.17[/tex]
Therefore, the pH of buffer is, 5.17
