The Chemistry of Life 31
(A) Isotonic solution 10 mm(B) Hypotonic solution 10 mm^10 mm^
(C) Hypertonic solution
Figure 2- 14 The effects of osmosis on red blood cells when placed in different concentrations of salt solutions.
(^) ®
Learning
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If a substance dissociates and forms an excess of H^1
ions when dissolved in water, it is referred to as an acid.
All acidic solutions have pH values below 7. The stronger
an acid is, the more H^1 ions it produces and the lower its
pH value. Because the pH scale is logarithmic, a pH
change of 1 means a 10-fold change in the concentration of
hydrogen ions. So lemon juice with a pH value of 2 is 100
times more acidic than tomato juice with a pH of 4.
A substance that combines with H^1 ions when dis-
solved in water is called a base or alkali. By combining