43. Solution to Chemistry Problem

7. Based on the data on the temperatures of the onset of crystallization of a two-component system:
1) construct a phase diagram (melting diagram) of the A - B system;
2) mark with points: I - liquid melt containing a % of substance A at temperature T1; II - melt containing a % of substance A, in equilibrium with the crystals of the chemical compound; III - a system consisting of solid substance A, in equilibrium with a melt containing b % of substance A; IV - equilibrium of phases of the same composition; V - equilibrium of three phases;
3) determine the composition of a stable chemical compound;
4) determine the qualitative and quantitative composition of eutectics;
5) plot all types of cooling curves possible for this system, indicate which compositions on the melting diagram these curves correspond to;
6) in what phase state are the systems containing c, d, e % of substance A at temperature T1? What will happen to these systems if they are cooled to temperature T2?
7) determine the number of phases and the number of conditional thermodynamic degrees of freedom of the system at the eutectic temperature and a molar content of component A of 95 and 5%;
8) at what temperature will the melt containing c % of substance A begin to solidify? At what temperature will it solidify completely? What is the composition of the first crystals?
9) at what temperature will the system containing d % of substance A begin to melt? At what temperature will it melt completely? What is the composition of the first drops of melt?
10) calculate the heats of fusion of substances A and B;
11) what component and in what quantity will crystallize from the system if 2 kg of melt containing a % of substance A is cooled from T1 to T2?

Option No.
Systems
Molar content of A, % Crystallization onset temperature, K Molar content. A, % Crystallization onset temperature, K

3 A – KI
B – CdI2
Mole fraction of A, % 0 10 30 45 47 49
Crystallization onset temperature, K 658 643 696 520 470 468
Mole fraction of A, % 53 55 60 65 80 100
Crystallization onset temperature, K 504 515 575 656 833 951

Option No. T1, K a b c d e T2, K
7 723 55 75 10 40 70.5 503

Option No.

Systems
Molar content of A, % Crystallization onset temperature, K Molar content. A, % Temperature
of the onset of crystallization, K

7 A – KI
B – CdI2 0
10
30
45
47
49 658
643
696
520
470
468 53
55
60
65
80
100 504
515
575
656
833
951

Option No. T1, K a b c d e T2, K
7 723 55 75 10 40 70.5 503