Acids, Bases, and the pH scale

Acids and Bases  A chemical compound that releases H + to solution is an acid.  A compound that accepts H + and removes it from solution is a base.

The pH Scale To describe the acidity of a solution, chemists use the pH scale. The pH scale is a logarithmic scale therefore, each pH unit represents a factor of 10 difference in [H + ].

Buffers Buffers are substances that resist pH change. Buffers  Accept H + ions when they are in excess  Donate H + ions when they are depleted Buffering Agents are commonly used in Biotech procedures.

The Significance of pH Most living cells have a narrow range of tolerance for pH The shapes of molecules such as proteins can be affected by pH causing denaturation and loss of function. pH is something that is controlled and regulated by all living organisms and is something that must be controlled for in virtually all biochemical experiments.

Measuring pH The pH of a substance can be determined in the following ways…  By using a pH meter—read the number.  By using pH paper (color patterns indicate pH).  By titrating the solution with precise amounts of base or acid in conjunction with a soluble dye, like phenolphthalein, whose color changes when a specific pH is reached.