analiticka hemija

verica161's picture

izracunati ph rastvora kome su koncentracije sircetne kiseline iznosi 0,4 mol/dm3 i natrijum acetata o,35 mol/dm3. kostanta kiselosti sircetne kiseline iznosi 1,74*10-5.

milicaradenkovic's picture

CH3COOH--------------->CH3COO- + H+

Ka=(CH3COO-)*(H+)/(CH3COOH)

1.74*10(-5)=0.35*(H+)/0.4

(CH3COOH)=0.4 mol/l

CH3COONa------------->CH3COO- +  Na+

(CH3COO-)=c(CH3COONa)=0.35 mol/l

(H+)=1.74*10(-5)*0.4/0.35=1.988*10(-5)

pH= -log(H+)=4.7