(a) ().
.
a = 1, .. .
1
1 Al2(SO4)3.
Al2(SO4)3 - , . . . :
Al2(SO4)3 2Al3+ + 3SO42-.
, 2 3 - Þ
[Al3+]=2×C = 2 /; [SO42-]= 3× = 3 /.
2
0.1 NaOH.
- ( ), , :
NaOH Na++OH- ;
-, ,
[OH-]= = 0.1 /,
= - lg [OH-]= 1,
pH= 14- = 13.
.
, , , .
3
0.2 .
a<1, :
H2SO3 HSO3- + H+,
1= [HSO3-]×[H+]/[H2SO3]= 1.6×10-2; (1)
HSO3- SO32- + H+,
Ka2= [SO32-]×[H+]/[HSO3-]= 6.3×10-8. (2)
, HSO3- H+, SO32- H+, ,
[HSO3-]+ 2×[SO32-]= [H+], (3)
[H2SO3]= C - [HSO3-]- [SO32-]. (4)
(1)-(4) , , Ka1>>Ka2. , + HSO3- , , . SO32-.
[+], [HSO3-] [H2 SO3]
(1) , + HSO3-, , = [+] = [HSO3-2], [H2 SO3]= - .. ,
1= 2 /( - )= 1.6×10-2
2 /(0.2- )= 1.6×10-2,
1 = -6.5×10-2 2 = 4.9×10-2. , .
[+] = [HSO3-] = 4.9×10-2 /, [H2 SO3]= 0.151 /,
a1 = [+]/ = 4.9×10-2 //0.2 / = 0.245, 24.5%.
[SO32-]
[+] [HSO3-] (2)
|
|
[SO32-]×[H+]/[HSO3-]= [SO32-] = 2 = 6.3×10-8 /,
a2 = [SO32-]/[HSO3-]= 6.3×10-8 /./ 4.9×10-2 / = 1.29 ×10-6.
: .
4
5%- ( r=0.97 /).
1). . 1 :
mp= V×r = 1000 ×0.97 / = 970 ;
m= mp×w = 970 ×0.05 = 48.5 ;
n= m/ = 48.5 /35/ =1.39 ;
=n/ V= 1.39 /1 = 1.39 /.
2). :
NH4OH NH4+ + OH-.
= [NH4+]×[OH-]/[NH4OH]= 1.8×10-5.
a = Ö(/) = a=Ö(1.8×10-5 /1.39) = 3.6 ×10-3;
a<<1, , . 1 -; a× , , -,
[-]= a× =3.6 ×10-3 × 1.39 / = 5.00×10-3 /,
= - lg[-] = - lg 5.00×10-3 = 2.30,
pH = 14-pOH= 14 -2.30 = 11.70.
: , a > 0.1, a =a2×/(1-a) (. 3), a..