Chemistry

Liquids


Linkage systems

If compounds are formed between two system components in the solid state, these compounds behave like pure substances and can crystallize out of the melt as separate phases (Laves phase). Intermetallic phases are particularly common and well investigated. The intermetallic Laves phase is formed in the magnesium / zinc system MgZn2.

The phase diagram can be composed of the two partial diagrams Zn/MgZn2and MgZn2/Mg think that qualitatively correspond to the SystemCd / Bi. The two parts show eutectics ((Fig. 1): A and B) with melting points of 380 and 347, respectively ° C. The eutectic mixtures consist of finely crystalline mixtures of MgZn2 andZn respectively MgZn2 and Mg.

The mole fraction of 0.33 Mg corresponds to the intermetallic phase MgZn2, the dystectic ((Fig. 1): C).MgZn2 melts at 590 ° C.

Note
You can see that the basic substances Mg,Zn and MgZn2 the highest melting points.
Note
Form several compounds or intermetallic phases, for example Cu2Mgand CuMg2, the diagram also contains several maxima.
Example aniline / phenol

Analogous relationships can also occur with completely different classes of compounds. The basic aniline and the acidic phenol form the salt aniline phenolate, in which the two components are present in a ratio of 1: 1:

The phase diagram of the phenol / aniline system is similar to that ofMg/Zn.


Video: Kontrol af motorrum og væsker - KørekortXperter (January 2022).