Calculation of initial pH

The initial pH of the solution can be calculated using the expression for the dissociation constant of acetic acid (CH3COOH):

Ka = [H+][CH3COO-]/[CH3COOH]

pKa = -log Ka

pH + pKa = log ([CH3COO-]/[CH3COOH])

pH = pKa + log ([CH3COO-]/[CH3COOH])

pH = 4.74 + log (0.01/0.01)

pH = 4.74

Addition of 0.01 mole CH3COONA

CH3COONA is the salt of weak acid CH3COOH. When it is added to the solution, it will undergo hydrolysis to produce CH3COO- and Na+ ions.

CH3COONA + H2O → CH3COO- + Na+ + H2O

The CH3COO- ion will react with H+ ions in the solution to form CH3COOH.

CH3COO- + H+ → CH3COOH

This reaction will shift the equilibrium of the dissociation of CH3COOH towards the production of H+ ions, leading to a decrease in pH.

Calculation of change in pH

The change in pH can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log ([CH3COO-]/[CH3COOH])

After the addition of CH3COONA, the concentration of CH3COO- ion will increase by 0.01 M, and the concentration of CH3COOH will decrease by 0.01 M.

[CH3COO-] = 0.02 M

[CH3COOH] = 0.00 M

pH = 4.74 + log (0.02/0.00)

pH = -1.63

The change in pH can be calculated as the difference between the initial and final pH:

Change in pH = final pH - initial pH

Change in pH = (-1.63) - 4.74

Change in pH = -6.37

The change in pH is -6.37, which means that the pH of the solution will decrease by 6.37 units after the addition of 0.01 mole CH3COONA. However, the negative value of change in pH is not physically possible, as pH cannot be negative. Therefore, the actual change in pH is the absolute value of -6.37, which is 6.37.

Final answer: The change in pH is 6.37 units.