The document discusses water, pH, and buffers. It covers the structure and polarity of water molecules, solubility in water, acids and bases, and how buffers maintain pH stability. Buffers work by having both weak acids and their conjugate bases reach equilibrium according to their dissociation constants in order to neutralize added acids or bases. The most important physiological buffers are bicarbonate and phosphate buffers that help regulate blood and intracellular pH.

1. Water, pH and Buffers

4. Water is a dipolar Molecule The approximate shape and charge distribution of water. Martin Chaplin, http://www.lsbu.ac.uk/water/molecule.html The two hydrogen atoms have partial positive ( δ + ) charges and the oxygen molecule has a partial negative (2 δ - ) charge. The result of unequal sharing is two electrical dipoles, one along each H-O bond.

7. Boiling and freezing point of water

10. Heme group (active site) in cytochrome f

17. Effect of extracellular osmolarity on water movement across a plasma membrane Effect of extracellular osmolarity on water movement across a man-made, selectively permeable membrane

27. Titration Curve for Acetic Acid and its Conjugate Base NaOH is added incrementally to HAc, and the pH of the mixture is measured. This value is plotted against the amount of NaOH expressed as the fraction of total NaOH required to convert all the HAc to its protonated form. At the midpoint of titration, the pH is equal to the pKa. The shaded zone is the region useful for buffering power, generally between 10% and 90% titration of a weak acid.