a. [H+] = 0,01.4,25% = 4,25.10^-4 —> pH = -lg[H+] = 3,37 b. CH3COOH ↔ CH3COO- + H+ 0,1 a………………….a…………a 0,1 – a…………..a………….a Ka = a.a/(0,1 – a) = 1,75.10^-5 —> a = 1,314.10^-3 —> pH = -lg[H+] = 2,88 c. NH3 + H2O ↔ NH4+ + OH- 0,1 a…………………..a………..a 0,1 – a…………….a………..a Kb = a.a/(0,1 – a) = 1,8.10^-5 —> a = 1,33.10^-3 —> pOH = 2,876 —> pH = 14 – pOH = 11,124 d. HCOOH ↔ HCOO- + H+ 0,1 a………………a………..a 0,1 – a……….a…………a Ka = a.a/(0,1 – a) = 1,6.10^-4 —> a = 3,921.10^-3 —> pH = -lg[H+] = 2,407 e. HF ↔ H+ + F- 0,1………….0,1 a……..a……….a 0,1-a…a…….a+0,1 Ka = a(a + 0,1) / (0,1 – a) = 6,8.10^-4 —> a = 6,709.10^-4 —> pH = -lg[H+] = 3,173