РАСТВОРИМОСТЬ И АМФОТЕРНОСТЬ ОКСИДОВ И

54.121:543
,
,
lta4455@yandex.ru
-
III
,
III
,
,
.
Solubility and amphotericity, thermodynamic calculation, oxides and hydroxides of IIIB group, aqueous media.
[1, 2]
.
III
III
.
III
[3, 4].
,
,
,
,
,
,
( )3.
Sc(OH)3 c
α-ScOOH [5].
(
[6]
)3
-
.
.
2
3
,
156
, [5, 6].
-
[5, 6].
III
-
,
.
[5−7].
-
,
[6]
(III).
,
«
,
»
,
La2O3 · n H2O [5, 6].
,
0,5
(∆G = +22
2
3(
) + 1,5
( )=
2
(
)3( )
)
ScO1,5
.
III
)3 (∆G = −34
(
YO1,5
−101
LaO1,5).
,
(
-
)3
1,5
)3( ) ⇄
(
( )+
1.5(
) + 1,5
Ks =
(
3+
), (
−
2
=a(
3+
( )+3
( )⇄
2
3+
( )⇄
3+
3+
)–
Ks
−
( ),
−
( )+3
3+
) · a3 (
(0,5Sc2O3),
−
( )+
−
( ),
(1)
( ),
) = const(T),
−
.
.
(1)
∆Gf 
∆Gf 
[1].
[8].
298
[4, 7].
,
157
 3,1, 4,8, 6,2
= d ln [M 3+] / d ln CM [9]
Sc2O3, Sc(OH)3, Y(OH)3
6,7.
=1
s  CM 
K S0
3
f M 3 f OH

Ks
f (M3+), f (OH−) –
0 = 1, 1, 2, 3, 4 –
2+
, ( )2+, ( )3
( )4−
[3, 9].
(III)
.
Sc2(OH)24+, Sc3(OH)54+ , Y3(OH)54+ La5(
[9, c. 23]
La(OH)3
4 (
Sc(OH)3
3,7(∆lg s = 0.02) 19
i OH 
i3
n
i0
La(OH)3
,
3+
(1);
−
;
La2OH5+, Y2(OH)24+,
< 1.
-
)96+ [6, 9]
6,5 ( = 0,99), Y(OH)3
= 0,80)
. % (∆lg s = 0,09),
 10−5
· −1
5,5 ( = 0,94)
0,6 (∆lg s = 0,003),
, [M3+],
0−14.
−

(
)
[1]
.
Ks = −lgKs, s −
. 1,
-
.
, [M(OH)3] –
25  .
Ks  ,
-
.1
[3, 10].
.
,
,
,
,
1
(
2).
La(OH)3
(42−96
. %).
Y(OH)3 Y(OH)2+.
158
III
.
.1
,
Sc(OH)3
-
1
25 
pKs
H2O

[3, 7]
Sc(OH)3*
29,8
29,7
Sc(OH)3· H2O
30,7
−
Sc(OH)3
32,72
33,0
*
S
[M(OH)3]
7,77 1,4·10
−5
1,3·10
7,07 1,6 ·10−7 1,3·10−7
−6
/
1
NaOH
s
/
8,05 1,1·10−4 1,0·10−4
−5
S,
NaOH
A
8,16 3,97
1,7
4,6·104
8,16 4,86
0,22
4,5·104
8,16 6,88 2,1·10−3 3,8·104
−6
8,16 5,66 0,034 4,3·104
7,02 3,8·10−8 3,0·10−8
8,16 7,51 4,8·10−4 3,7·104
α−ScOOH
31,6
31,5
ScO1.5*
33,4
−
ScO1.5
36,6
36,3
7,00 3,0·10−11 2,3·10−11 8,16 10,6 3,7·10−7 3,7·104
Y(OH)3*
22,77
−
8,62 4,6·10−6 1,2·10−6 10,31 5,68 2,0·10−4 1,3·102
Y(OH)3
24,45
24,50 8,07 5,6·10−7 3,2·10−8 10,31 7,43 3,6·10−6
α−YO1.5**
18,47
18,1
La(OH)3*
18,98
19,19 9,93 1,4·10−3 1,3·10−3 11,05 2,89 7,3·10−3
La(OH)3
21,6
21,7
La(OH)3 · H2O
22,6
−
7,43 2,4 ·10
2,1·10
10,2 3,4·10−2 3,3·10−2 10,31 1,47
−6
5,9
8,53 1,9·10−6 2,8·10−7 11,05 6,54 1,6·10−6
2,1
*
3,1·10
11,05 5,46 1,8·10
.
**
.
.1
(
(
 = 7,0−7,1),
 = 7,8−9,9).
,
,
–
(

3+
–
)3
s
Sc < Y < La (
Pi
13
−5
8,86 7,4·10
−6
19
3,1·102
,6
.
.1
[7]
69 % (Sc – O) 76 % (La – O)
.
s (3,8 / )
α−Y2O3
[5, 7].
[6]
,
).
Pi
,
Y2O3
159
,
Sc2O3,
,
La2O3.
Y2O3 (7 · 10−6
s
. 1).
/ ,
.
. 1)
,
s
s (1 · 10−6
/ [5])
ScOOH Sc2O3
Y2O3 La2O3
,
/ )
( .
α−ScOOH (2 · 10−6
-
2
3
[2].
s(
/ )
25 .
La(OH)3; 2 − La(OH)3; 3 – Y(OH)3;
4 – Sc(OH)3; 5 – ScO1,5
1–
n
)
15
(
~4
,
n>3
,
[2].
−
(
s
160
,
= − lg s
[1, 2],
25
(
-
)3
2
3
,
.
)3
s
.
-
.1,
−
-
(
NaOH)
Y(OH)3
-
.
La(OH)3
−

-
(
.
,
(
:
2
3).
. 1)
,
-
~5, 7 8 [5].
, La(OH)3
Sc(OH)3
.
,
[1, 2],
( > 1) NaOH)
14,7 (5
.
~4 · 104 (
)
(
(
NaOH
.
)3
Sc > La >Y.
Ks ,
−Ga2O3 [2],
4 5).
Sc2O3
(
5(
La3+
-
)4−
(
c
~20 6
. 1).
1 5
.
,
HClO4)
Y3+,
–
Sc < Y < La.
,
Sc2O3, Sc(OH)3 α−ScOOH
25 
5 NaOH
(
s (
. 1).
8 · 10−5, 0,6 8 / ) Sc2O3, Sc(OH)3 · H2O Sc(OH)3
(~0,1, 60 470 / ).
2+
ScOH ,
.
∆G298
298
(
–
)
:
(
)3 ( ) ⇄
2+
( )+2
−
( ),
(2)
161
(
)3 ( ) ⇄
(
(
Sc2O3 (2) – (6)
ScO1.5 ( ) + 1,5
)3 ( ) +
2
)3 ( ) ⇄
(
( )⇄
,
−
)2+ +
(
( ),
(3)
)3 ( ),
+
( )+
(4)
)4− ( ).
(
(5)
Sc(OH)3 ( )
:
( ).
2
2
(2)–(5),
(6)−(8)
(9)
298
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Sc(OH)3
20,0
11,4
3,86
13,7
−2,59
−7,98
−12,3
−0,30
Y(OH)3
18,6
12,9
7,47
19,5
−1,11
−9,42
−17,5
5,48
La(OH)3
16,1
10,8
5,51
18,9
−3,18
−11,9
−20,4
4,68
ScO1.5
26,6
18,0
10,5
20,3
4,02
−1,38
−5,67
6,31
YO1.5
−
−
−
−
−6,86
−15,2
−23,3
−
LaO1.5
−
−
−
−
−23,5
−32,1
−40,6
−
298
. 2,
[4, 7, 8, 10]
-
−Ga2O3 [2]).
-
,
( )3
Sc < Y < La.
(5)
Sc(OH)3 (
= 13,7,
298
:
(
)3 ( ) +
(
)3 ( ) + 2
(
( )⇄
+
)3 ( ) + 3
(
162
+
( )⇄
)3 ( ) +
+
2+
( )⇄
−
) 2+( ) +
(
3+
( )+2
( )+3
( )⇄ (
2
2
( ),
(6)
2
( ),
(7)
( ),
)4− ( )
(8)
(9)
.
.2
,
,
-
–
.
,
,
-
[5, 6].
1.
(
)3
,
.

La(OH)3 > Y(OH)3 > Sc(OH)3 > Sc2O3.
2.
(
-
)3,
25 
~4 · 104 ~6
> 1,
-
Sc > Y > La.
3.
8,16, 10,3 11,05
Sc(OH)3, Y(OH)3 La(OH)3 .
4.
,
Sc(OH)3 < Y(OH)3 < La(OH)3.
,
-
.
1.
,
2.
. .
[
]/ . .
//
. – 2009. –
III
. 189. − . 206−213.
, . .
III
[
]/ . .
//
163
. 194. − . 176−182.
3.
, . .C
.:
, 1989. – 448 .
4.
, . .
. .
, . .
, . .
5.
[
. – .:
, 1988–1995. – . 1. –
6.
,
. .
. .
, . .
,
, 2007. – 537 .
7.
, . .
. .
, . .
, . .
392 .
8.
, 1981. – 488 .
9.
, . .
. .
, . .
.–
10.
, . .
, . .
.–
. − 2011. –
[
.–
]/
. 4.
]/
.
[
] :
, 2006. – 685 .
. .
,
.
.:
.
. .
]/
.
.
.–
/
. .
. .
/
, 1983. –
. – .:
[
:
, 1988. – 294 .
[
]/ . .
, 1983. – 267 .
:
-
[
] /
. – . 1. – .:
.
[
]:
. – .:
, . .
[
.
, . .
] /
-
25  ,
2
3
,
–
Sc, Y, La.
***
The influence of hydrogen index pH on the molar solubility of M2O3 solid oxides
and their hydrates in aqueous alkaline and acidic media at 25 C, as well as the heterogeneous acid−base equilibria constants were calculated for stable crystalline hydroxides
M(OH)3 and oxides M2O3, where M = Sc, Y, La, by the thermodynamic method, taking
into account the formation of mono- and polynuclear hydroxo complexes.
164