Grama soli

pH=6.2 pa je {H+}=6.31*10(-7) mol/l

pOH=7.8 pa je {OH-}=1.58*10(-8) mol/l

C6H5COOH------------------>C6H5COO- + H+

C6H5COO- +H2O---------------->C6H5COOH+OH-

{C6H5COOH}={OH-}=1.58*10(-8) mol/l

Ka={C6H5COO-}*{H+}/{C6H5COOH}

6.5*10(-5)=6.31*10(-7)*{C6H5COO-}/1.58*10(-8)

1.03*10(-12)={C6H5COO-}*6.31*10(-7)

{C6H5COO-}=1.63*10(-6) mol/l

C6H5COOK------------>C6H5COO- + K+

{C6H5COOK}={C6H5COO-}=1.63*10(-6) mol/l

n(C6H5COOK)=1.63*10(-6) mol

m(soli)=n(C6H5COOK)*Mr=1.63*10(-6)*160=2.608*10(-4) g