.
, .
, , : )
∆ G = ∆ H - T ∆ S (, = const); (17)
)
∆ F = ∆ U - T ∆ S (V, T = const). (18)
/.
, (. .10). , ∆ G = - .
, , , .., .
, 1) , ; 2) , .
(), , .
(D G < 0 D F < 0).
, , , .4.
Δ G, /
∆ G > 0
. ∆ G = 0
∆ G < 0
. 4. ,
:
- ( = const, T = const): Δ G = 0,
- (V = const, T = const): Δ F = 0.
, ( ), :
∆ G = ∆ H - T ∆ S;
Δ F = ∆ U - T ∆ S.
: 1) , , ( ); 2) , .
|
|
, , .
(.. 2 3) , .. , .
. () , ( > 10000 ) - , , , , .
, , :
÷ ∆ H ÷ > ÷ T ∆ S ÷ ,
÷ ∆ H ÷ < ÷ T ∆ S ÷ - .
, ( = ) ( ¹ ) , Δ F, , ∆ G.
+ = + , , Δ G Δ H 0 298 D S 0 298, .19. ≠ 298 , . 20.
∆ G 0 298 = Δ H 0 298 - 298∙D S 0 298, (19)
∆ G 0 ≈ Δ H0 298 - T D S 0 298 . (20)
Δ G 298. Δ G 298 Δ 298:
∆ G 0298 = [∆ G 0298() + ∆ G 0298()] [∆ G 0298() + ∆ G 0298 ()]. (21)
, , , , .
, , . ∆ G = 0.
∆ G = Δ H - T D S = 0 (22)
= Δ H / D S . (23)
1.
t = 100. .
Si() + SiO2() = 2SiO()
.
D G 298 .
Si SiO2 SiO
∆ H 0298, / 0 -912 -438
S 0298, /∙ 19 42 27
∆ 0298 = [2∙(-438) [-912+0] = 36 ;
∆ S 0298 = [2∙(27) [42+19] = -7 /;
∆ G = ∆ H 0298 - T ∆ S 0298 =36 - 373×(-7)×10-3 = 38,6 .
|
|
, ∆ G , 373 . , SiO2 .
, SiO2 SiO , , , .. , ∆ G = 0.
= ∆ H 298 /∆ S 298 = 36/(-7.10-3)= -5143 .
, , .
2.
1 :
Fe3O4() + 4H2() = 3Fe() + 4H2O()
∆ 298 , / -1118 0 0 -241,8
.
:
∆ 298 = 4∆ 298 (2) ∆ 298 (Fe3O4) = 4(-241,8) - (-1118) = 150,8
3 , .. 3 ∙ 56 / = 168 .
1 :
168 Fe - 150,8 ;
1000 Fe - ;
= 897 .
3
, :
2BaO() + O2() = 2BaO2()
.
:
∆ 298 = 2∆ 298 (2) - (2∆ 298 () + ∆ 298 (2))
∆ 298 = -634,7∙2 - (-553,9∙2 + 0) = -161,6
∆ S 298 = 2 S 298 (2) (2 S 298 () + S 298 (2))
∆ S = 77,5∙2 (70,5∙2 + 206) = -191 / = - 0,191 /
∆ G = -161,6 + 0,191× .
∆ G 298 = -161,6 + 0,191×298 = -104,68 . ∆ G 298 < 0 .
∆ G = 0.
∆ G = -161,6 + 0,191 = 0
= - 161,6 - 0,191 = 846,07
846,07 , BaO2 .
4
250 25 , 44,08 /.
.
∆ S = D / .
250 250 /18 / = 13,88 . : 13,88 ∙ 44,08 / = 611,83 .
250 = 25 +273 = 298
∆ S = 611,83 / 298 = 2,05 .