Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 3. Water and life 20187137 Nguyễn Lê Hưng - Coggle Diagram
Chapter 3. Water and life
20187137 Nguyễn Lê Hưng
Water is the cradle of life
Structure and chemical properties of water
Structural formula: H − O − H
Structure of water: Bohr,“Space-filling” and “ball-and-tick”
Molecular formula: H2O
Four emergent properties of water
Ability to moderate temperature
Water absorbs heat from warmer air and releases stored heat to cooler air
Water can absorb or release a large amount of heat with only a slight change in its own temperature
Heat a measure of the total amount of kinetic energy due to molecular motion
Temperature measures the intensity of heat due to the average kinetic energy of molecules
Water’s High Specific Heat
water is 1 cal/g/oC
Water resists changing its temperature because of its high specific heat
can be traced to hydrogen bonding
Evaporation
transformation of a substance from liquid to gas
the heat a liquid must absorb for 1 g to be converted to gas
Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water
Floating of Ice on liquid water (expansion upon freezing)
Ice floats in liquid water because hydrogen bonds in ice are more “ordered,” making ice less dense
Cohesive and adhesion behavior
Cohesion: hydrogen bonds hold water molecules toghether
surface tension
Adhesion: an attraction between water and other substance
capillary action
The solvent of life (excellent solvent)
Solution: a liquid that is a homogeneous mixture
Solvent: the dissolving agent of a solution
Solute: the substance that is dissolved
Aqueous solution: one in which water
Water is a versatile solvent due to its polarity,which allows it to form hydrogen bonds easily
Hydrophilic: has an affinity for water
Hydrophobic have not an affinity for water
Acidic and basic conditions affect living organisms
A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other:
The pH Scale
pH = –log [H+]
Buffers
The internal pH of most living cells must remain close to pH 7
are substances that minimize changes in concentrations of H+ and OH– in a solution
Most buffers consist of an acid-base pair
Threatt
CO2
A warming of earth called the “greenhouse” effect
Acidification of the oceans; this leads to a decrease in the ability of corals to form calcified reefs
Acid precipitation
pH lower than 5.6
refers to rain, snow, or fog
can damage life in lakes, streams, and ocean