Raising or lowering the boiling or freezing point of a solution by adding solute.
Long video explaining why entropy is a measure of the number of states a system can take on (mathy, but mind-blowing).
Proving that a Carnot Engine is the most efficient engine.
More formal understanding of why a negative change in Gibbs Free Energy implies a spontaneous, irreversible reaction.
A look at why the "proof" of the relation between changes in Gibbs Free Energy and Spontaneity is wrong in many textbooks.
Empirical and Molecular Formulas from Stoichiometry.
Molecular and Empirical Forumlas from Percent Composition. Example 2.9 from Kotz Chemistry book.