water
DESCRIPTION
Water. Earth the Water Planet. Earth the Water Planet. Special Properties of Water. Universal Solvent Transparency Three Physical Phases Density and Temperature High Specific Heat High Heat of Vaporization Low Compressibility “Stickiness” of Water Molecules Viscosity. - PowerPoint PPT PresentationTRANSCRIPT
Water
Earth the Water Planet
Earth the Water Planet
Special Properties of Water Universal Solvent Transparency Three Physical Phases Density and Temperature High Specific Heat High Heat of Vaporization Low Compressibility “Stickiness” of Water Molecules Viscosity
Polarity of Water Molecules
Hydrogen Bonding Between Water Molecules
Hydrogen Bonding Between Different Molecules
Universal Solvent
Solution = A liquid in which two or more substances are homogeneously mixed.
Solvent = Fluid portion of a solution into which other substances are dissolved.
Solute = A substance that is dissolved into a solvent to produce a solution.
Universal Solvent
NaCl (sodium chloride)Dissolving Into Water
Universal Solvent
Universal SolventNaCl Dissolving Into Water
Universal SolventNaCl Dissolving Into Water
Protein Dissolving Into Water
Universal Solvent
Solubility of Solids In general, the solubility of solids increases
with increases in temperature.
Solubility of Gases In general, the solubility of gases decrease
with increases in temperature.
Importance to Living Things
Water is the solvent in which most of the chemistry of life takes place.
Transparency
Electromagnetic Radiation
Electromagnetic Radiation
Light Intensity and Depth in the Ocean
Spectral Characteristics of Light with Depth
Aquatic plants are able to live and photosynthesize beneath the surface of the water.
Animals are able to see below the surface of the water.
Changing spectral distribution of light with depth influences physiology and behavior of living things.
Importance to Living Things
Three Phases of Water
liquid gas
solid
Three Phases of Water
liquid gassolid
Ice vs Liquid Water
liquidicehydrogen bonds
Melting and Boiling Temperatures of Water
Colligative Properties Dissolved solids increase the boiling point
and decrease the freezing point.
Water exists in all three phases at temperatures found on Earth.
If water behaved like substances with similar molecular weight, water would exist only as a gas and it’s likely that the Earth’s gravity wouldn’t retain water.
Importance to Living Things
Density and Temperature Above 4°C the density of liquid water
decreases as the temperature increases.
As the temperature is decreased from 4°C to 0°C, the density decreases.
Water exhibits a density maximum of 1.0 grams/milliliter (g/mL) at 4°C.
Ice is less dense than water.
Density Behavior of Water
Specific Gravity
Ice floats on top of liquid water. If ice were more dense than liquid
water, then ice would sink, leading to a freezing-over of many lakes and streams.
Importance to Living Things
Ice Floats!
High Specific Heat
1.0 calories of absorbed heat energy will raise the temperature of 1.0 gram of water by 1.0°C.
Water can buffer the environment and living things against extreme changes in temperature.
Importance to Living Things
High Heat of Vaporization At 25°C, 1.0 gram of water must
absorb 580 calories of heat energy in order to be converted from a liquid to a gas.
Water vapor in the atmosphere moderates the Earth’s climate.
Living things may moderate their body temperatures via evaporation of water from their surfaces (evaporative cooling).
Importance to Living Things
Low Compressibility
Liquid water does not compress significantly into a smaller volume.
Water can provide shape and form to a living thing (hydrostatic skeleton). For some organisms a hydrostatic skeleton may facilitate movement.
Aquatic organisms may swim.
Importance to Living Things
Low Compressibility
“Stickiness” of Water Molecules
Cohesion
Adhesion
Surface Tension
Cohesion The binding together of like
molecules; the binding together of water molecules to each other via hydrogen bonds.
Adhesion The binding together of different
molecules; the binding of water molecules to other substances via hydrogen bonds.
Cohesion + Adhesion
Capillarity
Cohesion and Adhesion in Water Transport in a Plant
Importance to Living Things
Surface Tension
Importance to Living Things
Resistance of a Fluid to Flow
Viscosity
Colloids and Suspensions
The viscosity of water may be a significant force resisting movement in very tiny aquatic organisms.
The viscosity of water retards the rate at which small suspended particles may settle through it.
The viscosity of water may influence transport of fluids throughout an organism.
Importance to Living Things
Decomposition of WaterH2O H+ + OH-
1 in 107 water molecules will decompose this way in a container of pure water ( [H+] = 10-7 M).
Note that the concentration of H+ is equal to the concentration of OH-)
Definition of pH
pH = -log[H+]
pH of pure water = -log[10-7] = 7
Acids
HCl H+ + Cl-
Add excess H+ to the solution such that [H+] > [OH-].
Bases
NaOH Na+ + OH-
Remove H+ from the solution such that [H+] < [OH-].
pH Scale
Neutral 7Acidic <7Basic (alkaline) >7
Type of Solution pH Value
pH Scale
Buffers
Chemicals that minimize changes in the pH of a solution.
Enzymes (enzymes regulate chemical pathways in cells and tissues) and other proteins of living things are pH-sensitive.
The pH of physiological solutions may influence chemical equilibria.
Importance to Living Things
