The first step is to find the concentration of acetate in the solution, to do it, convert the given mass to moles using sodium acetate molar mass:
[tex]2.05gCH_3COONa\cdot\frac{1molCH_3COONa}{82.0343gCH_3COONa}=0.025molCH_3COONa[/tex]Now, divide the amount of moles by the volume in liters:
[tex]\frac{0.025molCH_3COONa}{0.057L}=0.44M[/tex]Finally use the equation of Henderson-Hasselbach to calculate the pH
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