Chapter 3 - Water and Life

polar molecule

charge unevenly distributed

cohesion

attraction between molecules of the same substance (water to water) through hydrogen bonds

surface tension

result of cohesion due to hydrogen bonding

measure of how difficult it is to stretch or break the surface of a liquid

cohesion contributes to:

transport of water and dissolved nutrients against gravity in plants

adhesion

clinging of one substance to another

kinetic energy

the energy of motion

thermal energy

random movement of atoms

a form of kinetic energy

temperature

average kinetic energy of the molecules

thermal energy of a body of matter

total kinetic energy

heat

thermal energy in transfer from one body of matter to another

calorie (cal)

convenient unit of heat
amount of heat it takes to raise the temperature of 1g of water by 1 degrees Celsius

specific heat

amount of heat that must be absorbed or lost to change its temperature by 1 degrees Celsius

water's specific heat

unusually high

breaking hydrogen bonds

heat must be absorbed

hydrogen bonds form

heat is released

high specific heat of water

stabilize ocean temperatures, creating a favorable environment for marine life

vaporization/evaporation

liquid to a gas

heat of vaporization

quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state

evaporative cooling

liquid evaporates, surface of the liquid that remains behind cools down

evaporative cooling of water contributes

to the stability of temperature in lakes and ponds

is liquid or solid more dense

less dense as a solid than as a liquid

at 0 degrees celsius: molecules of water do:

locked in a crystalline lattice

benefits of ice floating

so that ponds, lakes, and oceans could freeze solid

solution

homogenous mixture of two or more substances

solvent

dissolving agent of a solution

solute

substance that is dissolved

aqueous solution

one in which the solute is dissolved in water (water is the solvent)

hydration shell

sphere of water molecules around each dissolved ion

hydrophilic

with an affinity for water

will dissolve in water except if they're really big, like cotton

hydrophobic

nonionic and nonpolar repel water

molecular mass

sum of the masses of all atoms in a molecule

mole (mol)

exact number of objects

molar mass

grams/mole

molarity

number of moles of solute per liter of solution

reactivity of H+ and OH-

very reactive

acid

increases the hydrogen ion concentration
H+

base

reduce the H+ concentration by accepting hydrogen ions OH-

weak acids

acids that reversibly release and accept back hydrogen ions

pH formula

pH=-log[H+]

difference between pH

tenfold difference

buffer

substance that minimizes changes in the concentrations of H+ and OH-

ocean acidification

CO2 dissolves in seawater, lowers ocean pH