Understanding Colligative Properties

This collection of flashcards focuses on key terms and concepts related to colligative properties and their physical impacts on solutions.

Colligative Property

A property of a solution that changes directly as a solute is added.

Freezing Point Depression

A colligative property where solute particles lower the freezing point of the solvent.

Boiling Point Elevation

A colligative property where solute particles raise the boiling point of the solvent.

Vapor Pressure Depression

A colligative property where solute particles lower the vapor pressure of the solvent.

Osmotic Pressure

The pressure required to stop the flow of solvent across a semipermeable membrane.

Van't Hoff Factor (i)

The number of ions a solute dissociates into per formula unit.

Electrolytes

Chemical compounds that can dissociate into ions in an aqueous solution.

Nonelectrolytes

Compounds whose aqueous solutions do not conduct electricity.

Ionic Bonds

Type of bonds that compose electrolytes, involving the transfer of electrons.

Covalent Bonds

Type of bonds that compose nonelectrolytes, involving the sharing of electrons.

Solute

The substance that is dissolved in a solvent.

Solvent

The substance that dissolves the solute and is present in the largest amount.

Molality (m)

The number of moles of solute per kilogram of solvent.

Crystallization

The process by which solute particles form an organized crystal lattice.

Kf

The freezing point constant, used in calculations of freezing point depression.

Kb

The boiling point constant, used in calculations of boiling point elevation.

Dissociation

The process of breaking down a compound into its constituent ions.

Strong Electrolytes

Electrolytes that completely dissociate into ions in solution.

Weak Electrolytes

Electrolytes that partially dissociate into ions in solution.

Vapor Pressure

The pressure exerted by a vapor in equilibrium with its liquid or solid phase.

Osmosis

The movement of solvent molecules through a semipermeable membrane from a dilute to a concentrated solution.

Hydration

The process of surrounding solute particles with solvent molecules.

Colligative properties dependence

Colligative properties depend on the number of solute particles, not their identity.

Electrolyte examples

Common examples include NaCl, KBr, and CaCl2.

Nonelectrolyte examples

Common examples include sugar (C6H12O6) and ethanol (CH3OH).

Formula for Freezing Point Depression

ΔTf = i x Kf x m.

Formula for Boiling Point Elevation

ΔTb = i x Kb x m.

Vapor Pressure Equation

P = Xsolvent × P°solvent.

Vapor Pressure Lowering

The decrease in vapor pressure caused by the addition of a solute.

Osmotic Pressure Formula

Osmotic pressure can be calculated using the formula π = iCRT.

Molarity (C)

The number of moles of solute per liter of solution.

Properties of Solutions

Solutions exhibit unique properties that differ from those of pure solvents.

Effect of Solute on Freezing Point

More solute results in a lower freezing point.

Effect of Solute on Boiling Point

More solute results in a higher boiling point.

Dissociation Example for NaCl

NaCl dissociates into Na⁺ and Cl⁻, resulting in a van't Hoff factor of 2.

Dissociation Example for Ba(OH)2

Ba(OH)2 dissociates into Ba²⁺ and 2 OH⁻, resulting in a van't Hoff factor of 3.

Dissociation for Glucose (CH6H12O6)

Glucose does not dissociate, resulting in a van't Hoff factor of 1.

Dissociation for Al(NO3)3

Al(NO3)3 dissociates into Al³⁺ and 3 NO3⁻, resulting in a van't Hoff factor of 4.

Hydrogen Bonding

Strong intermolecular forces that occur in solutions, especially in water.

Raoult’s Law

States that the vapor pressure of a solvent is directly proportional to its mole fraction.

Colligative Effects

The effects that the addition of solutes have on the physical properties of solvents.

Concentration Units

Various ways (molarity, molality, percent) to express concentration of solutions.

Application of Colligative Properties

Used in understanding boiling point elevation and freezing point depression.

Boiling Point of Solutions

Solution boiling points are higher than those of pure solvents due to solute presence.

Freezing Point of Solutions

Solution freezing points are lower than those of pure solvents due to solute presence.

Electrolyte Behavior

Electrolytes behave differently in solutions compared to nonelectrolytes.

Chemical Conductivity in Solutions

Electrolytes can conduct electricity due to mobile ions.

Solution Examples

Examples may include salty water (NaCl in water) or sugary water (sugar in water).

Colligative Properties and Solvent Identity

The identity of the solvent does not affect the changes caused by solute particles.