Test 1 Intro to Bio + Water Pt. 2 Final Flashcards
homogeneous solution
A solution is a type of mixture made of two or more things (at least one liquid) in which all components are evenly distributed (dissolved)
heterogeneous mixture
a mixture made of two or more substances that are physically combined (mixed) together but not dissolved together (not chemical ycombined)
suspension
heterogeneous mixture in which some of the particles settle out of the mixture upon standing.
Ex: flour and water mixture, chalk and water mixture.
Heterogeneous mixture that does not dissolve and the different parts will separate.
colloid
A mixture in which very small particles of one substance are distributed evenly throughout another substance. Ex: Milk, paints, fog.
The particles are generally larger than those in a solution, and smaller than those in a suspension
pH scale
Hydrogen ion (H+1) is the basis of the pH scale.
Greater H+1 concentration = lower pH = Acidic
Lower H+1 concentration = higher pH = Basic
Ex. pure water is at middle of scale, concentration of H+ and H- ions is equal
Acid
a chemical that releases H+1 ions (has more)
pH below 7
base
Base: a chemical that accepts H+1 ions (has fewer)
pH above 7
buffer
a chemical that accepts/releases H+1 as necessary to keep pH constant
Weak acids or bases that can react with strong acids or bases to prevent sharp and sudden changes in pH
act as a reservoir for hydrogen ions, donating or removing them from solution as necessary
Offer protection from extreme pH levels
Produced naturally by organisms:
Organisms can’t tolerate much pH change
Cells function best within a narrow pH range
props of water
Polar molecule
Cohesion and adhesion
High specific heat
Density – greatest at 4C
excellent solvent of life
bonds within water molecules
hydrogen and oxygen in water molecule are bonded with covalent bonds
polarity of water
Within a water molecule, the bonds between oxygen and hydrogen are highly polar.
Water’s oxygen atom attracts electrons more forcefully than either of its hydrogen atoms, electrons are denser around the oxygen atom, which becomes somewhat negative charge
molecules that contain an unequal charge distribution, possess distinct positive and negative regions, or pole
Partial electrical charges develop:
- oxygen is partially negative
- hydrogen is partially positive
non polar molecules
lack regions of electric charge
electrons are evenly distributed
Hydrophilic
Polar molecules are hydrophilic, or “water loving”, attracted to water molecules and dissolve easily in water
hydrophobic
Nonpolar molecules are hydrophobic, or “water fearing”, repelled by water molecules and do not dissolve in water
hydrogen bonds
weak attractions between the partially negative oxygen of one water molecule and the partially positive hydrogen of a different water molecule.
Each water molecule can form hydrogen bonds with up to four neighbors.
They form, break, and reform with great frequency
water chemistry
The polarity of water causes it to be cohesive and adhesive.
Polarity unequal charge distribution in a molecule resulting in a – region and a + region
cohesion
water molecules stick to other water molecules through hydrogen bonding
adhesion
water molecules stick to other polar molecules by hydrogen bonding, the prop of water molecules to cling to any hydrophilic substance
organisms depend on cohesion
Cohesion & adhesion are responsible for the transport of the water column in plants against the pull of gravity
Capillary action – cohesion & adhesion working together to draw water up the veins of plants
Capillary action - substances having a hyrophilic surface, attraccting water molecules with enough force to overcome the pull of gravity, powered by adhesion
Related to plants ability to get water from their roots to the treetops
Capillary action brings water part of the way up, and adhesion and cohesion help to bring it the rest of the wy through the tree
surface tension
a measure of the force necessary to stretch or break the surface of a liquid, is related to cohesion.
Cohesion between molecules creates a film or layer that resists being separated, this property is called surface tension, permits things that are too dense to float to sometimes walk across the surface of water if they don’t disturb this layer
Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface.
water moderates temperature on Earth
It takes more heat to raise the temp of some substances than it does to raise the temp of others
(Specific Heat dependent)
When water is heated, its individual molecule cannot move faster until hydrogen bonds are broken, therefore water has a high specific heat, absorbs considerable heat before its temp raises markedly
Water stabilizes air temperatures by absorbing heat from warmer air and releasing heat to cooler air.
Water can absorb or release relatively large amounts of heat with only a slight change in its own temperature.
Prevention of temperature fluctuations that are outside the range suitable for life.
Coastal areas having a mild climate
A stable marine environment
specific heat
xthe amount of heat that must be absorbed or lost for one gram of a substance to change its temperature by 1oC.
evaporative cooling
The cooling of a surface occurs when the liquid evaporates
Water is an efficient cooling agent, b/c all hydrogen bonds must be broken water can’t change from liquid to gas until it is heated at very high temp
When water evaporates it takes with it much of of the heat it absorbed, evaporation can cool an organism or surface
This is responsible for:
Moderating earth’s climate
Stabilizes dentemperature in aquatic ecosystems
Preventing organisms from overheating
density of water
Most dense at 4oC
Contracts until 4oC
Expands from 4oC to 0oC
density of water:
Prevents water from freezing from the bottom up.
Ice forms on the surface first—the freezing of the water releases heat to the water below creating insulation.
When water reaches 0C, hydrogen bonds crystallize and lock in place, leaving more space between them (gets less dense)
Ice is about 10% less dense than water at 4oC.
