Chemistry · MU Sofia

2.1 Dispersions

Covers the classification of dispersions by particle size, placing true solutions, colloidal solutions, coarse dispersions and suspensions in order, followed by the mechanism of dissolution in stages and the factors that govern solubility. It then addresses temperature dependence of solubility with examples, strong versus weak electrolytes, and Ostwald's dilution law. Closing sections introduce Henry's law for gases, the van't Hoff relation, and colligative properties.

Inside: 12 sections · 8 labelled pictures · 20 flashcards · 6 min

Topic 6 of 42 in the MU Sofia syllabus for Chemistry (Medicine, Year 1). The free AceMed note covers it in 12 sections, about 840 words (6 min of reading), with 20 flashcards.

In this note

  1. Types of Dispersion
  2. Mechanism of Dissolution
  3. Solubility and Concentration of Solutions:
  4. Temperature dependence of solubility
  5. Solutions of electrolytes ( weak vs strong electrolyte )
  6. Degree of electrolyte dissociation
  7. Ostwald's dissolution law
  8. High-Yield Additions for Solutions & Dispersions
  9. Solubility of Gases in Liquids (Henry’s Law)
  10. Relation Between Solubility & Temperature (Van’t Hoff Equation)
  11. Degree of Dissociation (α) and Ostwald’s Dilution Law
  12. Colligative Properties

Types of Dispersion

  • A Solution:
  • Homogeneous dispersion where solute particles are uniformly distributed in a solvent.
  • Particle size < 1 nm.

Suspension:

  • Heterogeneous dispersion where solid particles are dispersed in a liquid medium.
  • Particle size: 100 nm.
  • Some common examples of suspensions are as follow:
  • Oil and water
  • Muddy water
  • Dust in air

Colloid:

  • Microheterogeneous dispersion.
  • Particle size: 1 nm - 100 nm.
  • Coarse Dispersions:
  • Particle size > 100 nm.
  • Includes suspensions, emulsions, and foams.
  • Prone to precipitation or floating due to significant particle size.
  • Colloidal Solutions:
  • Particle size: 1 nm - 100 nm.
  • Susceptible to precipitation or surface emergence upon prolonged residence or under external factors.
  • True Solutions:
  • Particle size < 1 nm.
  • Stable systems where the dispersed phase is broken down into ions or molecules.
  • Also known as molecular or ionic solutions.
  • Molecular and ionic solutions
  • Disperse medium in liquid solutions is the solvent, while the disperse phase is the solute.
  • Molecular solutions: Solute particles are individual molecules; no bonds are broken.
  • Ionic solutions: Solute particles are ions; bonds are broken upon dissolution.(Dissolution) is a spontaneous process favoured by energetics.

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