Midterm 2 Flashcards
9-13
What is Delta H vap ?
standard enthalpy of vaporization (or standard heat of vaporization)
standard heat of vaporization
What is the substance called if Pvap is large?
Volaile
As intermolecular forces increase, what happens to vapor pressure?
it decreases
What is Cp?
Heat capacity
What is fusion?
melting
1 atm = ? torr
1 atm = 760 Torr
What is equilibrium when talking about vapor pressure?
When the rate of evaporation = rate of condensation
What does vapor pressure represent?
The pressure of vapor when the system is at equilibrium.
Look at CHART A. Fill.
A: T1
B: T2
C: Molecules moving fast enough to vaporize at T1 and T2
D: T1
E: T2 > T1
F: U1
G:U2
H: Kinetic energy needed to overcome intermolecular forces in liquid
Gibbs Phase Rule:
Rule and what it means
F = C - P + 2
Phase = Componens - phases + 2
Tells you the “degrees of freedom”
What are the degrees of freedom?
The number of variables required to define the thermodynamic state of a system. Also, the number of variables that can be changed. P & T
Special Gibbs Phase Rule for azeotropic mixtures
F = (C - P + 2) - 1
Phase boundary lines
phase diagrams
when two phases are in equilibrium
Triple Point
phase diagrams
When all 3 phases exist simultaneously
Critical Temperature
The temp ABOVE which a vapor cannot be liquefied, no matter what pressure is applied
Critical Pressure
The pressure required to produce liquification AT the critical temperature
Critical Point
beyone this point the transition from one state to another involves neither true liquid nor vapor
Supercritical Fluids
Fluids where at the critical point, only one phase exists.
- phase lines split into a little U rotated 30* at the critical point
- heat of vaporization (delta H vap) is 0.
- a very dense gas that can act as solvent
Transient State
When a system is changing from one state to another, and has not yet reached a steady state. Like on a phase diagram.
Solute
The smaller (in mass) of the components in a solution, the material dispersed into a solvent.
Solvent
The major compnent of the solution, the material that the solute is dissolved into.
Solubility
The maximum amount that can be dissolved into a particular solvent to form a stable solution at a specified temperature.
Miscibility
The ability of two substances to dissolve in one another in any proportion.
