Introduction to Solutions and Solubility: Water- The universal solvent
December 5th, 2012
By: Ajaykumar Shanmugaraj
Summary: Today's lesson was an introduction to the new unit: Solutions and Solubility
  • Solvents, solutes and Solubility
  • Types of Solutions
  • Water- The universal solvent
  • Electrolytes
  • Miscible vs. Immiscible
Overview of Today's Lesson:
  • Students were introduced to a new topic which covers both solubility and solutions
  • Students were taught thoroughly about the components of a solution and the different types
  • Students were also taught that water is a universal solvent, and has unique properties

  • Solutions are composed of two things:
    • o Solvents: the substance that is larger quantity and does thimages (1).jpge dissolving
    • o Solutes: the substance that is smaller in quantity and is being dissolved
    • Concentrated solutions are those that are high in percentage of solute
    • Dilute solutions are those that are low in percentage of solute
    • Solubility: the maximum amount of solute that dissolves in a given quantity of solvent at a specific temperature. Measured in g/L, g/100L or mol/L
Types of Solutions:
  • Unsaturated Solution:

    • o A solution where more solute can be dissolved

    • Saturated Solution:
      • o A solution that has the maximum amount of solute dissolved in it. Therefore, no more of the solute can be added.
      • Supersaturated Solution:
        • download (1).jpgo A solution that has more solute that its maximum capacity at a given temperature and specified volume of the solvent
        • Aqueous Solution:
          • o Any compound dissolved in water
  • Water is polar so only polar solutes and compounds can dissolve in it. This is known as "like dissolves like"
  • Polar molecules and ionic compounds are soluble in water
  • Non polar solutes are not soluble in water because the solute-solvent attractions are weaker compared to the attractions between the solvent molecules. In other words, the intermolecular forces between the water molecules are too strong for the non-polar solutes to penetrate.
  • At times water can cause molecular substances to ionize by H-bonding to H2O or London dispersion forces.
  • Electrolytes are ions that conduct electricity. Ionic compounds dissolve in water to produce electrolytes. Electrolytes are important because they carry messages from and to the brain and also maintain cellular function.
  • Salt is referred to as any ionic compound
  • Solids have a higher solubility at higher temperatures whereas gases have higher solubility at lower temperature. In other cases, halogens and oxygen are slightly soluble in water because they are very reactive.
Miscible Vs. Immiscible:
  • Miscible:
  • Are referred as liquids that mix with each other
  • Water mixes well with polar solutes and ionic compounds
  • Immiscible:
  • Are referred as liquids that do not mix with each other
  • Non polar liquids do not dissolve in water
  • Any element that does not react with water is said to have a low solubility in water.
Useful References:

  • Section 8.2 (Page 376-380)
  • Section 8.3 (Page 382-389)
  • Read page 376-379 and Page 382-387
  • Page 381 #1-3 and Page 389 #2,3,4,6