Chapter 12 Printable Lecture Notes
Section 12.1: More reasons not to drink salt water
Tro, 3rd ed.
Dr. G Baxley
Section 12:2: Introduction to Entropy
Entropy is a topic that will be covered at length in Chem 201B. Entropy is a measure of energy
randomization, energy dispersal, and particle dispersal in a system.
Entropy is a measure of _____________________________________________________________________________________________
Systems with _______________________________________________ are more likely to exist
Solutions usually have more entropy than separate:
_________________________________________________________
_________________________________________________________
Section 12.3: Energetics of solution formation
Solutions:
In order for a solution to form, several energetic barriers exist:
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_________________________________________________________
_________________________________________________________
Energy is recovered with:
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_________________________________________________________
_________________________________________________________
The energetics of solution formation are complicated and are not relevant for our course.
Section 12.4: Factors that effect solubility
Solids:
Does sugar dissolve better in warm water or cold? _________________________________________________
As temperature increases, solubility of solids: ________________________________________________________.
Know these definitions: (section 12.4)
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Saturated: __________________________________________________________________________________
supersaturated: ____________________________________________________________________________
In saturated solutions, ____________________________________
is reached as solutes
________________________________________________________________
________________________________________________________________
Gases:
Does anything happen to the solubility of the gas as the pressure of the gas is increased?
______________________________________________
With high pressure:
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__________________________________________________________________________________________________________________
higher pressure = __________________________________________________________
Soda is bottled with a PCO2 = 4-10 atm.
• Opening bottle decreases the partial pressure of CO2
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solubility of CO2 _______________________________________________________
bubbles of CO2 __________________________________________________________
Are gases more soluble in warm liquids or cool liquids?
gases get ___________________________________________________________________________ increases.
Section 12.5: Units for solution concentration
ppm of component =
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mass of component in solution
× 106
total mass of solution
Parts per million (ppm) = ___________________________________________________________________________________
In water: 1 ppm = ___________________________________________________________________________________________
Parts per billion (ppb) = ____________________________________________________________________________________
Common units in water/air quality
See Figure 12.5 for units
Sample calculation (area)
Calculate ppm for the area of a credit card on a football field if the credit card measures 7.1 in2 and the
football field = 8.3x106 in2
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Calculation:
SLO water hardness, in terms of CaCO3, is 312 ppm. How many moles of CaCO3 are present in 1.00 L of tap
water?
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molality = ______________________________________________________________________
Stays constant with ___________________________________________________________
Similar to molarity for dilute, aqueous solutions
Calculation: What is the molality (m) when dissolving 25.0 g of calcium chloride in 250.0 mL of water?
Mole fraction: _____________________________________________________________________________________
Calculation: What is mole fraction when dissolving 25.0 g of calcium chloride in 250 mL of water?
Section 12.6: Colligative properties
Colligative properties depend on the _______________________________________________________________________________
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______________________________________________________________
______________________________________________________________
______________________________________________________________
Due to increased _____________________________________________________________________________________________________
Vapor Pressure
• As liquid boils, randomness ________________________________________________________________________________
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Solutes in solution also _____________________________________________________________________________________
Non-volatile solutes _________________________________________________________________________________________
vapor pressure _______________________________________________________________________________________________
Lower vapor pressure ______________________________________________________________________________________
depends only on # of particles of solute.
To calculate boiling point change, use ______________________________________________________________________________
_____________________________________________________________________________________________________________________
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________________________ of particles per mole of sucrose
________________________ of particles per mole of NaCl
Calculate the boiling point elevation for
• 0.90 m sucrose
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0.90 m CaCl2 (in H2O)
What molality of salt is needed to raise bp of water by 1.0 ºC?
What is the number of moles of NaCl needed to make 1.0 kg of salt water at this molality?
What is the mass of NaCl needed for about 3 L of solution?
Freezing Point
_____________________________ temperatures are needed to freeze a solution
Use formula ____________________________________________________________
___________________________________________________________________________
What is the freezing point of a 2.5 m solution of benzene in diethyl ether?
What is the concentration (in m) of ethanol in water if the freezing point is –4.3 Celsius?
Osmosis:
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Osmosis is the flow of a solvent from __________________________________________________________________________
Semi-permeable membrane: permits movement of the ______________________________________________________
Example: cell membranes, Gore-Tex
Which way will solvent molecules move, and what
happens to the concentration on each side?
Osmosis in cells
• ________________________________________ solutions: fewer ions than “normal”
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________________________________________ solutions: more ions
________________________________________: cells shrivel up as water leaves
________________________________________: cells burst as the swell up
To prevent crenation or hemolysis, IV (intravenous) solutions must be _______________________________.