.
, () , . - (a) , , . . (a @ 1).
: KnAm = nKm+ + mAn- (1)
(a <<1): KnAm Û nKm+ + mAn- (2)
, . , : K = [Km+]n. [An-]m / [KnAm] (3)
[Km+],[An-],[KnAm] [Km+], [An-] [KnAm] . K , . >>1; <<1.
, , . , H+. HCI, HBr HJ, . (..) , .. +6 +7, ; .. +5 , ( HNO3). .
1. :
H2SO3 Û H+ + HSO3-; : HSO3- Û H+ + SO32-.
:
1= [H+].[HSO3-] / [H2SO3] = 1,3.10-2; 2= [H+].[SO32-] / [HSO3 -] = 0,63.10-7 .
:
= 1.2 = [H+]2.[SO32-]/[H2SO3] =8.10-10.
, OH-. - (), . . . , H+, OH-. .
2. .
, , . ( ):
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H2O + H2OÛH3O+ + OH-, :
H2O Û H+ + OH- (4)
: = [H+].[OH-]/[H2O] = 1,8.10-16 ( 22 ) (5)
, [H2O] , : [H2O] = m/M.V = 1000/18 = 55,5/. , .[H2O] : .[H2O] = 1,8.10-16.55,5 =10-14. Kw.
Kw =[H+].[OH-] = 10-14 (6)
Kw , . Kw .
[H+] = [OH-] = = 10-7/ .
[H+] > 10-7/, .
[ H+] < 10-7 /, .
OH- : [OH-] < 10-7 /, [OH-] > 10-7 /.
H+ OH- , H+.
pH, : pH = -lg[H+]. (7)
pH = 7, pH<7, pH >7.
pOH, :
pOH = - lg [OH-] (8)
H + pOH = 14 (9)
pH pH- .
.
, , () (a),
= a2./1-a (10)
.
1-a @1, (10) :
= a2. (11)
, , : ( , ) (2) , .. ; ( ) (2) , .. . pH .
2. , 1 KCN ( ) HCN ( ) 0,1 .
: HCN ÛH+ + CN -.
: = [H+].[CN-]/[HCN] = 5.10-1 (. - 3). , , [H+]=[CN-]; , , [HCN] @. = [H+]2/ [H+] = Ö × C = Ö5.10-1 × 0,1 = 7.10-6. a =[H+] / a=7.10-5.
(7 ) pH = - lg[H+] = - lg 7.10-6 = 5,15.
0,1M HCN KCN 1/. : KCN Þ K+ + CN-, =CN -. - : CN- = C+[CN-].
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[CN-]= 7.10-6/, = 1/, >>[CN-] CN-@ C .
: [H+] =.[HCN]/CCN- = 5.10-10. 0,1/1= 7.10-11.
a = 5.10- 10, pH = -lg[H+] = -lg 5.10-11 = 10,3.
, pH HCN 5,15 10,3 KCN,.. HCN , ( a). KCN.
- , .