100ml of 0.1 M NaOH is added to 100 ml of a 0.2 M CH3COOH solution. The pH of the resulting solution will be (pka=4.74)
Millimole of 100ml of 0.1 M NaOH=100x0.1=10 millimole.
Millimole of 100 ml of a 0.2 M CH3COOH =100x 0.2=20 millimole.
Now it is a Buffer.
100ml of 0.1 M NaOH is added to 100 ml of a 0.2 M CH3COOH solution. The pH of the resulting solution will be 4.74.