Acids, Bases, & pH TSW differentiate between acids and bases, and explain the importance of pH to organisms

Acids Substances that increase the number of Hydrogen ions (H+) in solution

Bases Substances that increase the number of Hydroxide ions (OH-) in solution Substances that reduce the number H+ ions in a solution

pH Scale Used to measure the degree of acidity of a substance Ranges from 0-14 pH = 7 is neutral pH < 7 is acidic pH > 7 is basic

pH of Common Substances

Good to know… The pH scale is a measure of H+ ions in solution A low pH corresponds to a high concentration of H+ ions A high pH corresponds to a low concentration of H+ ions

pH Scale (cont.) pH scale is logarithmic A change of one pH number actually represents a TENFOLD change in [H+] Example: pH 3 is 10x more acidic than pH 4 pH 3 is 100x more acidic than pH 5

Buffers A weak acid or base that can react with strong acids or bases to help prevent sharp, sudden changes in pH

Why are buffers important? Accept H+ ions when they are in excess Donate H+ ions when they have been depleted Many biological reactions produce acids and bases, therefore the presence of buffers helps to keep the pH at a constant level Help maintain homeostasis