Chapter 13- Properties of Solutions

What are solutions?

Homogenous mixtures of two or more pure substances

How are attractions involved when forming a solution?

• Stronger the solute-solvent, greater solubility of a solute in a solvent

• Gases in the table only exhibit dispersion force

What factors affect solubility (4)?

• Solute-solvent

• Interactions

• Pressure (for gaseous solutes)

• Temperature

What are supersaturated solutions?

• Solvent holds more solute than normally possible at that temp

• Unstable, uncommon solutions

How does solubility involved with organic molecules in water?

• Polar organic molecules dissolve in water better than non-polar

• Hydrogen bonding increases solubility

What are miscible and immiscible?

• Miscible = liquids that mix in all proportions

• Immiscible = liquids that do not mix in one another

What is the biological importance of solubility?

• Fat soluble vitamins are non-polar + readily stored in fatty tissue

• Water soluble vitamins need to be included in daily diet

What is Henry’s Law?

• The solubility of a gas is proportional to the partial pressure of the gas above the solution

• S_g = kP_g 

What is the impact of temperature on solubility?

• Solids = as temperature increases, solubility increases

• Gases = as temperature increases, solubility decreases

What are the types of solution concentration (3)?

• Saturated

• Unsaturated

• Supersaturated

What are the units of concentration (6)?

• Mass percentage

• Parts per million (ppm)

• Parts per billion (ppb)

• Mole fraction

• Molarity

• Molality

How does temperature impact molality and molarity?

• Molality (m) = does NOT vary with temperature

• Molarity (M) = varies with temperature + volume changes

What are colligative properties and give examples (4)?

• Properties that depend only on quantity, not identity

• Vapor-pressure lowering, boiling-point elevation, freezing point depression and osmotic pressure

What is Raoult’s Law?

• Vapor pressure of a volatile solvent is the product of the mole fraction of the solvent times the vapor pressure of the pure solvent

• P solution = X solvent (P° solvent)  

What is the Van’t Hoff Factor?

• The amount of particles that remain together is dependent on the concentration of the solution

• Takes into account dissociation in solution

What is osmosis?

Net movement of solvent molecules from solutions of low to high concentration across a semi-permeable membrane

What is osmotic pressure and under what circumstance does it not occur?

• Applied pressure to stop osmosis (colligative property)

• If two solutions separated by semi-permeable membranes have the same osmotic pressure, no osmosis will occur

What are the types of solutions (3)?

• Isotonic = same osmotic pressure (solvent passes same rate both ways)

• Hypotonic = lower osmotic pressure (solvent leaves at higher rate than enters)

• Hypertonic = higher osmotic pressure (solvent enters at higher rate than leaves)

What is crenation and hemolysis?

• Crenation = RBCs shrivel was water leaves cell in hypertonic solution

• Hemolysis = RBCs grow until they burst in hypotonic solution

What are colloids and how do they relate to solutions?

• Suspension of particles larger than individual ions or molecules, too small to be settled out by gravity

• Ions can adhere to surface of hydrophobic colloid

• Aids in emulsification of fats/oil in aqueous solutions

What is Brownian Motion?

Motion of colloids due to numerous collisions with the much smaller solvent