pH . ( ) , :
w = 1014 (b ), .
. :
H3PO4 → H2PO4 → HPO42 → PO43
K1 K2 K3
, .
PO43 : PO43- → HPO42- → H2PO4- → H3PO4. : K1 = w / 3; K2 = w / 2; K3 = w / 1.
pH , , 0 /.
Na3PO4 → 3Na+ + PO43
0 30 0
PO43 h1 (h1<<1), . (PO43) = h1 0
PO43 + H2O ↔ HPO42 + OH
0 / ½ ê - ½ -
[PO43-] = 0 . =½ ê [HPO42-] = h1 0 ½ [OH] = h1 0
= 0 (1 h1)
PO43 , 1 = ,
h1 = , [OH] = h1 0 = pOH = - lg [OH]= =(), pH = 14 pOH.
, (1 << h1) , < 103, 0 > 0,001 /; .
, . , , , , .
Na2HPO4 → 2 Na+ + HPO42, HPO42
) III HPO42 ↔ PO43 + +; 3(34) = 1,261012
) HPO42 + H2O ↔ H2PO4 + OH = w / 2(34) =
= 1014 / 6,34108 = 1,57107.
, HPO42 .
1. , h (NH4Cl)=0,01 /3.
:
1) NH4Cl HCl NH4OH ; .
NH4Cl + H2O = NH4OH + HCl
NH4+ + H2O Û NH4OH + H+ - +, .. .
2) :
|
|
,
w , w =10-14 (25 0); b (NH4OH) ( ), b (NH4OH)=1,7410-5.
3) h :
,
c .
4) + :
5)
: NH4Cl 5,7510-10; 2,410-4; 5,62.
2. , , (3)=0,1/3, (3)=1,810-5.
:
1) CH3COOK CH3COOH KOH , :
CH3COOK + H2O = CH3COOH + KOH;
H3COO- + H2O Û CH3COOH + OH- -, .
2) :
,
.
2) h :
,
0 .
3) - - :
4)
: CH3COOK 5,610-10; 7,510-5; 8,88.
3. . , 10 200 3 , 0,01 %.
:
1) NaHCO3 :
NaHCO3 + H2O = NaOH + H2O + CO2
HCO3- + H2O Û OH- + H2O + CO2
2) - - :
, h , (NaHCO3) :
,
3)
: = 9,78.