Solution Notes
2 Parts of a Solution
Solute
Solvent
Why won’t water and Oil Mix?
Like dissolves like
Water is a ________________ molecule and therefore dissolves substances that are _______
Oil is a _____________ molecule and therefore dissolves substances that are ____________
What about soap?
Types of Attractions:
Solute Solute
Solvent Solvent
Solute Solvent
The Dissolution of liquids in liquids
Miscibility
Polar liquids tend to dissolve _________________ liquids
Why does the mixture of Sulfuric acid and water get hot?
Why when mixing acids and water do you put the water in the container first?
How do gases dissolve?
CO2
O2
HF, HCl, HBr, HI
How can I speed up the rate of dissolving?
Saturated
Equilibrium
Supersaturated
How does temperature affect solubility?
Endothermic Solids
Exothermic Solids
Gases
Thermal Pollution
Henry’s Law
Molality =
𝑴𝒐𝒍𝒆𝒔 𝒐𝒇 𝑺𝒐𝒍𝒖𝒕𝒆
𝒌𝒈 𝒐𝒇 𝑺𝒐𝒍𝒗𝒆𝒏𝒕
How many grams of H2O must be used to dissolve 50.0 grams of sucrose to prepare a 1.25 m
solution of sucrose C12H22O11?
What is the molality of a solution that contains 128 g of CH3OH in 108 g of water?
Colligative properties
Physical properties that depend on the ________________ not the kind of solute particles.
Vapor Pressure ____________________
Boiling point ___________________
Freezing Point ____________________
Osmotic Pressure
Vapor Pressure
Raoult’s Law – Vapor Pressure of a solvent is directly proportional to the mole fraction of the
solvent.
Psolvent = Xsolvent P0solvent
Psolvent = Xsolute P0solvent
Sucrose is a nonvolatile, nonionizing solute in water. Determine the vapor pressure lowering
at 25C of the 1.25m sucrose solution that contains 128 g of CH3OH in 108 grams of water. The vapor
pressure of pure water at 25C is 23.8 torr.
Volatile liquids
•
Pa = Xa P0a
•
Pb = XbP0b
•
Ptot = Pa + Pb…
•
Ptot = XaP0a + XbP0b
At 40C the vapor pressure of pure heptanes is 92 torr and the vapor pressure of pure octane is 31 torr.
Consider a solution that contains 1.00 mol of heptanes and 4.00 mol of octane. Calculate the vapor
pressure of each component and the total vapor pressure above the solution.
Calculate the mole fractions of heptanes and octane in the vapor that is in equilibrium with the
solution
Boiling Point Elevation
Tb = Kb x m
Predict the boiling point of the 1.25m solution of water.
Freezing Point Depression
Tf = Kf x m
Calculate the freezing point of the 1.25m solution of sucrose in water.
A 1.20 g sample of an unknown covalent compound is dissolved in 50.0 g of benzene. The
solution freezes at 4.92C. Calculate the molecular weight of the compound.
Either camphor (C10H16O, MW = 152 g/mol) or naphthalene (C10H8, MW = 128 g/mol) can be
used to make mothballs. A 5.2 g sample of mothballs was dissolved in 100. grams of ethyl
alcohol, and the resulting solution had a boiling point of 78.9C. Were the mothballs made of
camphor or napthalene? (Pure ethyl alcohol has a boiling point of 78.41C and a Kb = 1.22C/m)
How do Ionic Solutions Change it?
With an Ionic solution the ______________ _______________ it breaks into, the _________
the effect
Osmotic Pressure
The pressure required to push water molecules back across a _______________ membrane
 = MRT
Higher the temperature, ______________________ the osmotic pressure.
R = 0.0821 for atm or 62.36 for torr
What osmotic pressure would the 1.25m sucrose solution exhibit at 25C. The density of this
solution is 1.34 g/ml. 50 g of sucrose and 117 g of H2O
Pepsin is an enzyme present in the human digestive tract. A solution of a 0.500 g sample of
purified pepsin in 30.0 ml of aqueous solution exhibits an osmotic pressure of 8.92 torr at 27C.
Estimate the molecular weight of pepsin.
Colloids
Solution – A _______________________ mixture of two substances where ____________
settling occurs
Suspension – A ___________________ mixture of two substances where _________________
settling occurs
Colloidal dispersion – A ________________ mixture of two substances where
________________ settling occurs.
Tyndall Effect
The _________________ of __________________ as it passes through a colloid
Emulsifying agents
Hard Water
Contains Ca2+, Mg2+, or Fe3+
Phosphate in Detergents