colligative properties

Solution

Homogeneous mixture of two or more substances existing in a single phase with uniform composition and properties

Homogeneous mixture

Mixture with uniform composition and properties throughout

Heterogeneous mixture

Mixture consisting of two or more phases

States of solutions

Solutions can exist as gases liquids or solids

Mixture classification by composition

Gas mixtures liquid mixtures and solid mixtures

Gas mixture

Mixture of gases such as air

Liquid mixture

Mixture of liquids such as blood

Solid mixture

Mixture of solids such as rocks

Mixture classification by appearance

Heterogeneous and homogeneous mixtures

Heterogeneous mixture by particle size

Mixture with particle size larger than 500 nm

Real solution

Homogeneous mixture with particle size smaller than 1 nm

Colloid

Mixture with particle size between 1 and 500 nm

Dilute solution

Solution with at least 100 solvent molecules per one solute molecule

Law of dilute solutions

Properties depend only on the quantity of solute not on its nature

Concentrated solution

Solution where solute molecules interact and laws of dilute solutions do not apply

Physical behavior of solutions

Qualitatively similar to pure solvent but quantitatively different

Colligative properties

Properties that depend only on the number of solute particles

Examples of colligative properties

Vapor pressure depression boiling point elevation freezing point depression osmotic pressure

Vapor pressure

Pressure exerted by vapor molecules in equilibrium with liquid or solid phase

Raoult law

Partial vapor pressure equals vapor pressure of pure component multiplied by mole fraction

Mole fraction

Ratio of moles of one component to total moles in mixture

Partial pressure

Pressure exerted by an individual component in a mixture

Total vapor pressure

Sum of partial pressures of all components

Vapor pressure depression

Lowering of vapor pressure due to presence of nonvolatile solute

Cause of vapor pressure depression

Solvent solute attraction makes escape of solvent molecules harder

Raoult law for nonvolatile solute

Psolution equals mole fraction of solvent times vapor pressure of pure solvent

Positive deviation from Raoult law

A B interactions weaker than A A and B B interactions; endothermic formation

Negative deviation from Raoult law

A B interactions stronger than A A and B B interactions; exothermic formation

Freezing point depression

Decrease in freezing point proportional to molality

Freezing point depression formula

Delta Tf equals Kf times m

Boiling point elevation

Increase in boiling point proportional to molality

Boiling point elevation formula

Delta Tb equals Kb times m

Molality

Moles of solute per 1000 g of solvent

Kf

Molal freezing point depression constant

Kb

Molal boiling point elevation constant

Kf for water

1.86 degree Celsius kilogram per mole

Kb for water

0.512 degree Celsius kilogram per mole

Molar mass determination

Calculation based on colligative properties such as freezing point depression

Molar mass formula

M equals Kf times g divided by delta Tf

Osmosis

Flow of solvent through semipermeable membrane to equalize solute concentration

Direction of osmosis

Solvent moves from low solute concentration to high solute concentration

Osmotic pressure

Pressure required to stop osmosis

Osmotic pressure height formula

Pi equals h times rho times g

Osmotic pressure gas law formula

Pi V equals n R T

van t Hoff law

Pi equals c R T

van t Hoff factor

i equals number of particles formed per formula unit

Colligative properties of ionic solutions

Colligative effects multiplied by van t Hoff factor

van t Hoff factor for NaCl

i equals 2

van t Hoff factor for Al2(SO4)3

i equals 5

Osmolarity

Total concentration of dissolved particles in osmol per liter

Isotonic solution

Intracellular osmotic pressure equals extracellular osmotic pressure

Hypertonic solution

Extracellular osmotic pressure greater than intracellular

Hypotonic solution

Extracellular osmotic pressure lower than intracellular

Isotonic saline concentration

0.9 percent mass volume or 0.15 mol per dm3 or 0.3 osmol per dm3

Reverse osmosis

Solvent flow opposite to osmosis caused by applied pressure greater than osmotic pressure

Application of reverse osmosis

Desalination of water

Colloid definition

Mixture containing dispersed particles between 1 and 500 nm

Colloids classification

Microheterogeneous mixtures

Association colloids

Colloids formed by amphiphilic molecules

Function of amphiphilic colloids

Solubilization of hydrophobic molecules

Drug delivery role of colloids

Controlled loading targeting and extended release of drugs