PHYSICAL CHEMISTRY IN BRIEF

CHAP. 7: PHASE EQUILIBRIA [CONTENTS] 222

(s 2 )+(s 3 )

(s 2 )+(l)

(l)

E 1

E 2

Tt′

Tf2

T

0 x 1 x′ 1 1 0 x′ 1 x 1 1

Tf1

T

Tf2

Tf1

E

(s 2 )+(s 3 ) (s 3 )+(s 1 )

A

B

B

C

D

(l)+(s 1 )

F

(l)

P T

P

T′

a) b)

Obr. 7.15: Dependence of the temperatures of freezing and melting on composition for two-
component systems whose components form a compound in the solid phase. In case a) the compound
is stable at the melting temperature, in case b) it is unstable at the melting temperature. Individual
letters denote the following regions and points, A: (s 2 ) + (l); B, C: (s 3 ) + (l); D: (s 1 ) + (l); E, E 1 , E 2 :
eutectic points; P: peritectic point, F: (s 1 ) + (s 3 ).