U1 Chapter 3: Water and Life Flashcards
Polar Molecule
Overall, the molecule’s charge is unevenly distributed
Cohesion
When hydrogen bonds hold the substance together
Surface Tension
A measure of how difficult it is to stretch or break the surface of a liquid
Adhesion
The clinging of one substance to another
- adhesion of water by hydrogen bonds to the molecules of cell walls help counter the downward pull of gravity
Kinetic Energy
The energy of motion, atoms and molecules have kinetic energy because they are always moving (although not necessarily in any particular direction)
Thermal Energy
Kinetic energy associated with the random movement of atoms or molecules
Temperature
Represents the average kinetic energy of the molecules in a body of matter, regardless of volume, whereas the thermal energy of a body of matter reflects the total kinetic energy, and thus depends on the matter’s volume
Heat
Thermal energy in transfer from one body of matter to another
Calorie (cal), unit of heat
A calorie is the amount it takes to raise the temperature of 1 g of water by 1 degree Celsius
- it is also the amount of heat that 1 g of water releases when it cools by 1 degree celcius
- joule (J) = 0.239 cal
- 1 cal = 4.184 J
Specific Heat
Amount of heat that mut be absorbed or lost for 1 g of that substance to change its temperature by 1 degree Celsius
Heat of Vaporization
The quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state
Evaporative Cooling
As a liquid evaporates, the surface of the liquid that remains behind cools down (its temperature decreases)
- occurs because the “hottest” molecules, those with the greatest kinetic energy, are the most likely to leave as a gas
Solution
A liquid that is a completely homogenous mixture of two or more substances
Solvent
The dissolving argent of a solution
Solute
The substance that is dissolved
Aqueous Solution
One in which the solute is dissolved in water; water is the solvent
Hydration Shell
The sphere of water molecules around each dissolved ion
Hydrophilic
Any substance that has an affinity for water
- polar molecules
Hydrophobic
Substances that do not have an affinity for water
- nonionic and nonpolar (or otherwise cannot form hydrogen bonds) actually seam to repel water
Molecular Mass
The sum of the masses of all the atoms in a molecule
- mole (mol) represents an exact number of objects: 6.02 x 10^23 which is also called Avogadro’s number
Hydrogen Ion (H+)
A single proton with a charge of 1+
- the water molecule that has lost a proton is now a hydroxide ion (OH-)
Acid
A substance that increases the hydrogen ion concentration of a solution
Base
A substance that reduced the hydrogen ion concentration of a solution
pH Scale
A measure of hydrogen ion concentration equal to -log[H+] and ranging in value from 0 to 14
Buffer
A substance that minimizes changes in the concentrations of H+ and OH-
Ocean Acidification
When CO2 dissolves in sea water and reacts with the water to form carbonic acid, which lowers ocean pH
- alters the delicate balance of conditions for life in the oceans
