zadatak

KAsO2+H2O-------------->HAsO2+KOH

pH=11.3 a pOH=14-11.3=2.7

{OH-}=10(na - pH)=10(na - 2.7)=2*10(-3) mol/l

KAsO2-------------->K+ + AsO2-

Kb=Kw/Kk=1*10(-14)/6.3*10(-10)=1.6*10(-5)

AsO2- + H2O------------>HAsO2 + OH-

Kb={OH-}*{HAsO2}/{AsO2-}

{OH-}={HAsO2}=2*10(-3) mol/l

1.6*10(-5)*{AsO2-}=2*10(-3)*2

{AsO2-}=4*10(-6)/1.6*10(-5)=0.25 mol/l

{KAsO2}={AsO2-}=0.25 mol/l. Ja mislim da je ovo resenje mada nisam sigurna.