Chapter 10 Solution Formation
Terms in this set (32)
the heat content of a system at constant pressure (H)
Factors that are attributed to solution formation include:
enthalpy of solution which is related to intermolcular forces, and entropy which is a given property of nature
The analogy of relating intermolcular forces with change in H is
"when you move the molecules apart it is like pulling on a spring" Work needs to be done to overcome intermolcular forces.
Step one of the process of forming solutions:
The solute must be expanded, the energy required for this is delta H1. Endothermic
Step two of the process of forming solutions:
The solvent must be expanded, the energy required for this is delta H2
Step 3 of the process of forming solutions:
The solvent and solute are superimposed and the "spring is released"; this is the pay-off phase energy is given off and delta H is negative.
Steps one two and three of forming solutions:
describe hess's law and obtain the delta H of the solution.
delta H1 + delta H2 + delta H3 = delta H solution.
"ideal solutions" are the result of
very similar intermolecular forces in terms of strength between solute and solvent, delta H solution = 0 or is very close to 0.
"non ideal" solutions are the result of
solute or solvent intermolecular forces that are way stronger or weaker that the others. Usually the size of H3 is either way greater or less than than the sizes of the other two.
tell tale signs of a "non ideal solution"
-volume of the solution decreases (is not the sum of solute/solvent volumes).
-Delta H of the solution is less than or greater than 0
Colligative properties are
vapor pressure lowering, boiling point elevation, freezing point depression, osmotic pressure
Vapor pressure lowering
Boiling point elevation
the temperature difference between a solution's boiling point and a pure solvent's boiling point
freezing point depression
the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent
pressure that must be applied to prevent osmotic movement across a selectively permeable membrane
Colligative properties depend on
concentration of solute molecules and not composition (identity).
Which of the following concentrations will most affect colligative property?
A): 0.4M NaCl
B): 1.37M KCl
C): 0.002M NaCl
D): 1.02M KCl
B): highest concentration affects colligative properties the most.
True/ False: "Two solutions with the same value for osmotic pressure are isotonic"
True: No movement across the membrane will occur
Van Hoff's factor (i) is only used when ____ are present in solutions
ions/ electrolytes, which include poly-atomic compounds.
m in Boiling point elevation and freezing point depression formulas stands for
M in osmotic presssure formula stands for
X in vapor pressure lowering (raoult's law) formula stands for
mole fraction= moles solute/ total moles solution
CaBr2 i =
when asked for a change in vapor pressure what formula do I use?
Vapor Pressure Lowering (raoult's law)
When asked for the boiling or freezing points of a solution or are given values for K, what formula should I use?
Boiling point elevation, or Freezing Point depression
For boiling point elevation change in T =
Tb solution - Tb solvent (100 if H2O)
For Freezing point depression change in T =
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