Ako pomjesamo

Daniraa's picture

ako pomjesamo 100cm3 rastvora pOH=2 sa 900cm3 rastvora sa pH=7  dobit cemo rastvor ciji je

a)ph=9

b)pOH=9

c)pH=11

d)pH=7

e)ph=3,5

zlaja99's picture

Pozdrav!

pOH=2

V1=100 cm3=0.1 L

pH=7

V2=900 cm3=0.1 L

------------------------------------------------------------------------------

n(OH-)=V*c=0.1L *0,01mol/L =0,001mol=10^-3 mol

n(H+)=V*c=0.9 L*0,0000001=0,00000009 mol

U visku su OH- joni:

nv=0.001-0.00000009mol=0.00099991mol

Vu=0.1 L+0.9 L=1 L

[OH-]=nviska/Vu=0.00099991mol/L=0.00099991 mol/L= 9.9991*10^-4 mol/L

pOH=-log(9.9991*10-4 )=4-log9.9991=4-0.99=3.00

pH=14-3.0=11