Properties of Solutions Notes

Properties of Solutions

Definition of a Solution

  • A solution is a homogeneous mixture of two or more substances.

  • Composed of one or more solutes dissolved in a solvent.

    • Solute: Lesser quantity component (e.g., sugar in water).

    • Solvent: Largest quantity component (e.g., water).

  • Aqueous solutions have water as the solvent.

Characteristics of Liquid Solutions

  • Clear and Transparent: No visible solute particles.

  • Can be colored or colorless.

  • True Solutions: Particles are homogeneously mixed, cannot be filtered out.

  • Colloidal Dispersions: Medium particle sizes that scatter light (Tyndall effect).

  • Suspensions: Heterogeneous mixtures with larger particles that settle.

Types of Solutions

  • Electrolyte Solutions: Formed from soluble ionic compounds that dissociate into ions, conducting electricity (e.g., NaCl in water).

  • Nonelectrolyte Solutions: Non-dissociating molecular solutes that do not conduct electricity (e.g., glucose in water).

Solubility

  • Degree of Solubility: Amount of solute that can dissolve at a specific temperature.

  • Factors Influencing Solubility:

    • Polarity: "Like dissolves like" principle.

    • Temperature: Generally increases solubility for solids and liquids; opposite for gases.

    • Pressure: Has a notable effect on gas solubility in liquids.

  • Saturated Solutions: Contains maximum solute at given temperature.

  • Supersaturated Solutions: Unstable solutions containing more solute than needed for saturation.

Solubility and Equilibrium

  • Establishes dynamic equilibrium between dissolved and undissolved solute.

  • Rate of dissolution equals rate of precipitation when equilibrium is reached.

Henry's Law

  • Describes gas solubility in liquids: M = kP.

    • M = molar concentration of gas in liquid.

    • P = partial pressure of the gas above the solution.

    • k = Henry’s law constant (depends on temperature).

Concentration Calculations

  1. Mass/Volume Percent (% m/V): (grams of solute/mL of solution) x 100%.

  2. Mass/Mass Percent (% m/m): (grams of solute/grams of solution) x 100%.

  3. Parts per Thousand (ppt) and Parts per Million (ppm): Based on part-to-whole ratios.

  4. Molarity (M): Number of moles of solute per liter of solution (mol/L).

  5. Colligative Properties: Depend on solute particle concentration, including properties like boiling point elevation and freezing point depression.

Unique Properties of Water

  • Water is considered a universal solvent due to its polarity.

  • Has a high boiling point due to hydrogen bonding, useful in biological systems.

  • Essential for transport processes in cells, dissolving a variety of substances effectively.

Electrolyte Concentration

  • Electrolytes: Substances that dissociate into ions in solution and conduct electricity.

    • Molar concentration indicates the number of individual ions in solution, essential for biological functions.

  • Milliequivalents/Liter (meq/L): Useful for small amounts of ions, focusing on charge instead of mass.

Practical Applications

  • Importance of balancing osmotic pressure in medical treatments like IV fluids and oral rehydration therapies.

  • Knowledge of colligative properties and osmotic pressure critical for biological systems and treatment protocols.