Question

Determinati pH-ul urmatoarelor solutii:
a) solutie de Hl 10^-3 M (Ka=10^11)
b) solutie de CH3COOH 10M ( Ka=1,8*10^-5)
c) solutie de NH3 0.01 M (K NH4+=5,6*10^-10)

Answer 1

a)  [H⁺] = √(Ka·c) = 10⁻⁷      pH = 7
b) [H⁺] = √(1,8·10⁻⁴) = 1,34·10⁻²    pH = 2 - lg1,34 = 2-0,063 = 1,936
c) [HO⁻] = √(5,6·10⁻¹²) = 2,366·10⁻⁶     [H⁺] = 10⁻¹⁴ /(2,366·10⁻⁶) = 4,226·10⁻⁹
pH = 9 - lg4,226 = 9 - 0,626 = 8,374