Question | Answer |
Phase | A state of matter that is uniform throughout, not only in chemical composition but also in physical state |
Constituent | A chemical species (ion or molecule) |
Component | A chemically independent constituent of a system |
Variance F; degree of freedom | The number of intensive variables that can be changed independently without disturbing the number of pases in equilibrium |
Phase rule | F=C-P+2 |
Thermal analysis | A technique for detecting phase transitions that takes advantage of the effect of the enthalpy change during a first-order transition |
Vapor pressure of an ideal solution | p=p*b + (p*a -p*b) X xa |
Composition of the vapor | ya= xa X p*a / [p*b + (p*a - p*b) X xa]
yb=1-ya |
Total vapor pressure of a mixture | p=p*a X p*b / [p*a + (p*b - p*a) X ya] |
Isopleth | A line of constant composition in a phase diagram |
Tie line | A line joining two points representing phases in equilibrium |
Lever rule | Allows for the calculation of the relative amounts of two phases in equilibrium (n[alpha]l[alpha]=n[beta]l[beta] |
Temperature-composition diagram | A phase diagram in which the boundaries show the composition of the phases that are in equilibrium at various temperatures |
Azeotrope | A mixture that boils without change of composition |
Partially miscible liquids | Liquids that do not mix in all proportions at all temperatures |
Upper critical solution temperature | The highest temperature at which phase separation occurs in a binary liquid mixture |
Lower critical solution temperature | The temperature below which the components of a binary mixture mix in all proportions and above which they form two phases |
Eutectic | The mixture with the lowest melting point; a liquid with the eutectic composition freezes at a single temperature |
Eutectic Halt | A delay in the cooling while the eutectic freezes |
Incongruent melting | Occurs when a compound melts into its components and does not itself form a liquid phase |