Question

Zadania z chemii z ph

Answer 1

1.
a)   HNO3-----> H+   + NO3-
     [HNO3]=[H+]=[NO3-]=0,001mol/dm3
pH=-log[H+]
pH=-log0,001
pH=3
b) H2SO4----> 2H+ + SO42-
[H2SO4]=[SO42-]=[H+]/2=0,001mol/dm3
[H+]=2* 0,001=0,002 mol/dm3

pH=-log[H+]
pH=2,7
zad.2
a)
NaOH-----> Na+ + OH-
[NaOH]=[Na+]=[OH-]=0,01mol/dm3
pOH=-log[OH-]
pOH=2
pH=14-pOH
pH=14-2=12
b)
Ca(OH)2----> Ca2+ + 2OH-
[Ca(OH)2]=[Ca2+]=[OH-]/2=0,001mol/dm3
[OH-]=2* 0,001=0,002mol/dm3
pOH=-log[OH-]
pOH=2,7
pH=14-pOH
pH=11,3
zad.3
CH3COOH<--> CH3COO- + H+
Cm=0,01mol/dm3
a=1,5%

stęzenie początkowe kwasu znamy
a=[H+]/[CH3COOH]*100%
1,5=[H+]/0,01 *100%
[H+]=1,5*10^-4mol/dm3
pH=-log[H+]
pH=3,82

zad.4
a) pH=11----> pOH= 14-11=3
[OH-]=10^-3

Ca(OH)2----> Ca2+ + 2OH-

[Ca(OH)2]=[OH-]/2
[CaOH2]= 10^-3/2=5*10^-4 mol/dm3

b)

pH=10
pOH=14-10=4
[OH-]=10^-4

Ca(OH)2----> Ca2+ + 2OH-

[CaOH2]=2[OH-]
[CaOH2]=10^-4/2=5*10^-5 mol/dm3