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Rensselaer Polytechnic Institute: Chemical Equilibrium
This site from the Rensselaer Polytechnic Institute provides an introduction to chemical equilibrium, covering equilibrium expressions, the pH scale, and presenting how to plot log concentration diagrams.
Frostburg State University
General Chemistry Online: Faq: Acids and Bases
Click the basic questions regarding acids, bases, and pH to view the answers. There are sections on basic concepts, buffer solutions, pH calculation, equilibrium constants, indicators, neutralization reactions, and titrations.