4. 1. Cohesion & adhesion
2. Low density solid
3. Solubility: a good solvent
4. High specific heat capacity
5. High heat of vaporization & fusion
6. Ionization: determines pH

5.  Cohesion:
 the clinging of a substance to itself
 hydrogen bonds between water molecules
holding water together
 Adhesion:
 the clinging of one substance to another
 E.g. Meniscus: hydrogen bonds between
water molecules and the glass of a test tube

7.  A measure of how difficult it is to break the
surface of a liquid
 Surface tension is one of the results of
cohesion in water
 Video:
A National Geographic video showing how a lizard employs the

8.  Water is most dense at 4oC
 Ice is less dense than water
 Water is the only type of
matter which becomes less
dense when a solid

10. Aquatic life
 When the temperature
of the atmosphere falls
below 0oC, the water at
the surface gradually
freezes to ice
 The water under the ice
remains at 4oC

11.  Amount of heat energy needed to increase
the temperature of a substance by 1oC
 Water has a high specific heat capacity:
 Water is capable of absorbing a lot of heat
without increasing in temperature
 Demonstration: water balloon

13.  Help organisms maintain constant body
temperature
 Large bodies of water have moderating
effect on nearby land temperature

15.  Heat of vaporization: amount of heat a
liquid must absorb to be converted to a gas
 Heat of fusion: amount of heat a solid must
absorb to be converted to a liquid
 Water has high heat of both vaporization and
fusion
 Relevance: sweat

16.  Hydration shell
 Some biologically significant solutes
include salts, sugars, proteins, vitamins

17. Hydration Shells

19.  Many molecules are able
to dissolve in water.
 Organic matter may be
hydrophilic or
hydrophobic.

20.  H2O  H+ + OH-
 Reversible
 pH = -log[H+]
 Relevance: Organisms are very sensitive to
pH changes

21. Is water an acid or a base?
H 2O + H 2O H3O+ + OH-

22. Is water an acid or a base?
conjugate
base acid
H 2O + H 2O H3O+ + OH-
acid conjugate
base

23.  Acid
 compounds that will donate a proton in solution
 results in a negative charge
 Base
 compounds that will receive a proton in solution
 results in a positive charge