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1. Cohesion & adhesion2. Low density solid3. Solubility: a good solvent4. High specific heat capacity5. High heat of vaporization & fusion6. Ionization: determines pH
Cohesion: the clinging of a substance to itself hydrogen bonds between water
molecules holding water togetherAdhesion:
the clinging of one substance to another E.g. Meniscus: hydrogen bonds between
water molecules and the glass of a test tube
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 water property of high surface tension
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
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
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
Help organisms maintain constant body temperature
Large bodies of water have moderating effect on nearby land temperature
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
Hydration shellSome biologically significant
solutes include salts, sugars, proteins, vitamins
Hydration Shells
Many molecules are able to dissolve in water.
Organic matter may be hydrophilic or hydrophobic.
H2O H+ + OH-
ReversiblepH = -log[H+]
Relevance: Organisms are very sensitive to pH changes
Is water an acid or a base?
H2O + H2O H3O+ + OH-
Is water an acid or a base?
H2O + H2O H3O+ + OH-
acid conjugate base
baseconjugate
acid
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