AP Bio - Water and Life Chapter 3

Polar Covalent Bonds

Oxygen is more electronegative than hydrogen

Polar molecule

charge is unevenly distributed

Cohesion

hydrogen bonding keeps h2o molecules close to each other creating surface tension

adhesion

clinging of one substance to the other

Surface Tension

Difficult its to stretch or break the surface of a liquid

Thermal energy

Random movement of atoms or molecules

Temperature

kinetic energy in a body of matter

heat

transfer from one body of matter to another

calorie

convenient unit of heat

kilocalorie

used to raise heat the temp. of 1 kg of water by 1*C

Specific heat of a substance

heat that must be absorbed or lost by 1 g of that substance to change its temp by 1*C

Heat of Vaporization

Heat a liquid must absorb for 1 g

Evaporative cooling

“hottest” molecules (greatest kinetic) leave as gas

Solution

Liquid that is a completely homogeneous mix of 2 or more substances

Solvent

the dissolving agent of a solution

Solute

substance that’s dissolved

Aqueous Solution

One in which the solute is dissolved in water

hydration shell

sphere of water molecules around each dissolved ion.

hydrophilic

substance that has an affinity for water

Hydrophobic

Doesn’t have an affinity for water

Molecular Mass

The sum of the masses of all the atoms in a molecule

Molarity

The number of moles of solute per liter of solution

Hydrogen Ion

A hydrogen atom participating in hydrogen bond between 2 H2O molecules shift from one molecule to the other hydrogen atom leaves its electrons behind

Hydroxide Ion

Single portion with a charge of 1+ the water molecule that lost a proton

Hydronium Ion

Which has a charge of 1- the proton binds to the other water molecules

Acid

Substance that increase the hydrogen ion concentration of a solutions

Base

Substance that reduces the hydrogen ion concentration of a solution

pH

concentration of H+

Buffer

Substance that minimizes changes in the concentrations of H+ and OH- in a solution

Ocean Acidification

The decreasing pH of ocean waters caused by the absorption of excess atmospheric carbon dioxide, primarily from the burning of fossil fuels.