puferi

sosa95's picture

Zdravo,imam problem sa ovim zadatkom.koliko je ph acetatnog pufera nastalg rastvaranjem 820mg CH3COONA U 100ML rastvora CH3COOH KONCETRACIJE 0,5MOL/L?K(CH3COOH)=2 PUTA 10 NA MINUS 5...DA LI MOZE OBJASNJENJE?

Niki1995's picture

m(CH3COONa)=820mg=0.82 g

n(CH3COONa)=m/Mr=0.82/82=0.01 mol
V=100mL=0.1 L
c(CH3COONa)=n/V=0.01/0.1=0.1mol/L

H+=K * c(CH3COOH)/c(CH3COONa)
H+= 2*10(-5) * 0.5/0.1
H+=2*10(-5) * 5
H+= 10*10(-5)
H+= 10(-4)
pH=-log10(-4)
pH= 4