.
CH3COOH CH3COO- + H+
, , a,
[CH3COO-] = [H+] = aC
[CH3COO-] = C - aC
a<<1 K=ca2 蠠
, .
( ).
:
2 + + -- + 55,90 /.
:
, :
[H2O]= n(H2O)/1 = 1000 0,9971/18,015 = 55,5 /,
0,9971/ - , 18,015 / - .
, :
K[H2O] = 1,8×10-16 × 55,5 = 10-14 = [H+] × [OH-] = KH2O 堠 .
:
t,C | 10 | 22 | 30 | 100 |
KH2O | 0,4×10-14 | 1,0×10-14 | 1,9×10-14 | 74×10-14 |
- : [H+] = [OH-] = = 10-7 /.
[+] > [OH-]; [H+] >10-7 /.
[H+] < [OH-]; [H+]< 10-7 /.
, [+] , [OH-] , .
(10-9, 10-13 / ..) , . ( ) ,:
= lg[H+]
, [H+] × [OH-]= 10-14, : + = 14
22 = = 7.
< 7.
> 7.
- , ph . , .
| , | ||
3,2 4,5 | |||
. | 8,2 10,0 | ||
6,0 9,0 |
, .
|
|
. , :
3 3N | 4,7 | |
N24 N24 | 6,5 | |
N4 N41 | 9,25 |
+, - , .
: CH3COOH CH3COONa. : CH3COOH CH3COO + H+ :
Ka= = 1.8 10
CH3COO : [CH3COO ] C. , [CH3COOH] C, C .
Ka= ;
[H+] = Ka ;
pH = lg[H+] = pKa lg (),
pKa = - lg Ka.
, , .
, :
CH3COOH + NaOH = CH3COONa + H2O ( , ):
pH = lg[H+] = pKa - lg ();
CH3COONa + HCl = CH3COOH + NaCl,
pH = lg[H+] = pKa - lg ().
, , .
, , (B). (B ) (Bb).
Ba =
Bb =
Ba Bb ; Ca Cb ; pH 1 pH 2 ; Va and Vb .
26. pH 0.01 M NaOH.
. NaOH , :
NaOH Na+ + OH-
[OH-] = C(NaOH) = 10-2 /.
[H+] = 10-14/[OH-] = 10-12 /.
pH = lg [H+] = 12.
27. pH 0.01 M of CH3COOH.
. , : CH3COOH CH3COO- + H+
[H+] = a×C(CH3COOH)
, ,
, K(CH3COOH) = 1.75×10-5,
/
pH = lg [H+] = lg (4.18×10-4) = 4 lg(4.18) = 3.38.
28. pH , 0.01 / CH3COOH 0.1 / CH3COONa.
|
|
. CH3COOH CH3COO- + H+
( )
CH3COONa CH3COO- + Na+
( )
pH = lg [H+] = lg (1.75×10-6) = 6 lg(1.75) = 5.76.