This video explains the concept of equilibrium using a couple of examples everyone should be familiar with: dissolving sugar in water, and water evaporating out of a cup. Also covered: why is it called "dynamic" equilibrium? Pay attention, this is going to be a short-answer question on your quiz!
Le Chatelier's Principle -- Concentration
The wording of this principle -- something about systems in equilibrium moving to reduce disturbances -- can be very confusing. But it turns out the questions for this principle are pretty straightforward (and always the same), so by the end of this video you should be able to say with certainty which direction the equilibrium is "pushed" when you raise or lower the concentration of a particular reactant or product.
Le Chatelier's Principle -- Pressure
This video covers problems just like the previous Chatalier Principle, except that this time rather than changing the concentration of one of the compounds, the disturbance will be increasing or decreasing the pressure of the chamber in which the reaction is taking place. Warning: applies to gases only!
Le Chatelier's Principle -- Temperature
Like the other Chatalier videos, except this time we're dealing with -- you guessed it -- Temperature! Basically, this video tells you how to use the enthalpy of a reaction to deduce changes in equilibrium concentrations vis-a-vis baseline when the temperature of the system is increased or decreased. Basically.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)