Penjelasan:

a. 200 ml NH3 0,1 M dengan 100 ml HCl 0,1 M.

Mol NH3 = M x V = 0,1 x 200 = 20 mmol

Mol HCl = 0,1 x 100 = 10 mmol

Persamaan Reaksi:

NH3 + HCl ---> NH4Cl

20 10 -

10 10 10 mmol

10 - 10 mmol

basa lemah bersisa, larutan garamnya bersifat penyangga basa.

[OH-] = Kb x mol basa / mol garam

= 10^(-5) x 10 / 10

= 10^(-5)

[H+] = Kw / [OH-]

= 10^(-14) / 10^(-5)

= 10^(-9) M

pH = 9

b. 150 ml CH3COOH 0,1 dengan 100 ml NaOH 0,1 m

mol CH3COOH = 0,1 x 150 = 15 mmol

mol NaOH = 0,1 x 100 = 10 mmol

persamaan reaksi:

CH3COOH + NaOH ---> CH3COONa + H2O

15 mmol 10 -

10 10 10 mmol

5 mmol - 10 mmol

asam lemah bersisa, garamnya bersifat penyangga asam.

[H+] = Ka x mol asam / mol garam

= 10^(-5) x 5 / 10

= 0,5 x 10^(-5)

= 5 x 10^(-6)

pH = 6 - log 5