Question

Determinati concentratia molara a unei solutii de NaOH cu pH=10 si a unei solutii de NH3 cu pH=10 (Knh4+=5,6×10 la puterea -10).VA ROG MULT SA MA AJUTATI !!!!!!!!!!!!PLS DE 10 ORI

Answer 1

NaOH:
pH=10: {H+} = 10^ -10 mol/l
{OH-} = c NaOH
K H2O = {H+}*{OH-}
{OH-} = K H2O / {H+} = 10^ -14 / 10^ -10 = 10^ -4 mol/l
c NaOH = 10^ -4 mol/l

NH3:
pH=10: {H+} = 10^ -10 mol/l
K NH4+ = 5,6*10^ -10
{H+} = √ K H2O*K NH4+ / c NH3
{H+}^2 = K H2O*K NH4+ / c NH3
c NH3 = K H2O*K NH4+ / {H+}^2
c NH3 = 10^ -14 * 5.6*10^ -10 /  10^ -20
c NH3 = 5.6*10^ -24 / 10^ -20
c NH3 = 5.6*10^ -4 mol/l