Solutions and Mixtures: Types, Properties, and Separation

Posted on Jan 7, 2025 in Chemistry

Solutions: Properties and Characteristics

A solution is a homogeneous mixture of two or more components. It is indistinguishable to the naked eye and has a uniform composition.

The components of a solution are the solute and the solvent.

  • Solute: The substance that is dissolved and is present in a smaller quantity.
  • Solvent: The substance that dissolves the solute and is present in a greater quantity.

Solubility is the maximum amount of solute that can be dissolved in a fixed amount of solvent at a given temperature.

Types of Solutions

  • Dilute solutions: Contain a small proportion of solute.
  • Concentrated solutions: Contain a large proportion of solute.
  • Saturated solutions: Cannot dissolve any more solute at a given temperature.

Concentration of Solutions

Concentration is the quantitative expression that indicates the amount of solute in a solution.

Factors Affecting Solubility

  • Solubility of solids in liquids increases with temperature.
  • Solubility of gases in liquids decreases with temperature.
  • Solubility of gases in liquids increases with pressure.
  • The greater the contact surface, the faster the dissolution.
  • The greater the agitation, the faster the dissolution.

Formulas for Calculating Concentration

  • % Mass = (Mass of Component / Mass of Solution) * 100%
  • % Volume = (Volume of Component / Volume of Solution) * 100
  • g/L = Mass of Component / Liters of Solution
  • Molarity (M) = Moles of Component / Liters of Solution

Note:

  • L = Liter
  • V = Volume
  • M = Mass
  • Density (D) = m/v
  • M = d * v
  • V = m/d

Examples:

  • Pure substance: Water
  • Homogeneous mixture: Seawater, minerals, alloys
  • Heterogeneous mixture: Milk, gelatin

Separation Techniques for Mixtures

Some techniques for separating the components of a mixture:

  1. Screening or Sieving: To separate solids of different sizes.
  2. Filtering: To separate solid and liquid particles by passing the liquid through the pores of a filter paper, retaining the solid.
  3. Decanting: To separate immiscible liquids.
  4. Distillation: To separate miscible liquids with different boiling points.
  5. Crystallization: To separate a solid dissolved in a solvent. The solvent is evaporated, and the solid crystallizes on the bottom and walls of the crystallizer.

Mixtures: Definition and Types

Mixing is the union of two or more substances. They can be separated by physical processes such as evaporation, filtration, decantation, distillation, and crystallization. There are two types of mixtures:

Heterogeneous Mixtures

Heterogeneous mixtures are those in which we can distinguish the components with the naked eye. They also have different properties from one point to another in the mixture. Examples include water and oil, water and sand, oil and salt, granite (quartz, feldspar, and mica), and oil.

Homogeneous Mixtures (Solutions)

Homogeneous mixtures have the same properties at every point of the mixture, and their components are indistinguishable to the naked eye. Examples include air (nitrogen (N2), oxygen (O2), argon (Ar), water vapor (H2O(g)), carbon dioxide (CO2), sulfur dioxide (SO2)), and blood (H2O, blood cells, hemoglobin, oxygen (O2), iron (Fe)).

Pure Substances: Elements and Compounds

Pure substances are formed by a single type of substance and have an invariable composition and defined properties. They can be of two types:

Elements

Elements are pure substances that cannot be decomposed into other substances by physical or chemical methods. Examples: O2, N2, Ar, Fe, Ag, Au, C.

Compounds

Compounds are pure substances formed by the combination of two or more elements. They can be separated by chemical methods. For example, H2O can be decomposed into hydrogen and oxygen through a process called electrolysis.