Water and Life Practice Flashcards

Vocabulary flashcards covering the emergent properties of water, thermal energy, concentration measurements, and pH balance from the Campbell Biology Chapter 3 lecture.

Polar molecule

A molecule, such as water, where the overall charge is unevenly distributed.

Hydrogen bond

A bond formed when the slightly positive hydrogen atom of one water molecule is attracted to the slightly negative oxygen atom of another water molecule.

Cohesion

A phenomenon where hydrogen bonds hold water molecules together, helping to transport water against gravity in plants.

Adhesion

An attraction between different substances, such as between water and plant cell walls.

Surface tension

A measure of how hard it is to break the surface of a liquid; water has a high measure due to hydrogen bonding.

Kinetic energy

The energy of motion.

Thermal energy

The kinetic energy associated with the random motion of atoms or molecules.

Temperature

A measure of energy that represents the average kinetic energy of the molecules in a body of matter.

Heat

Thermal energy in transfer from one body of matter to another.

Calorie (cal)

The amount of heat required to raise the temperature of $1\,g$ of water by $1^\circ C$.

Joule (J)

A unit of energy where $1\,J = 0.239\,cal$ or $1\,cal = 4.184\,J$.

Specific heat

The amount of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1^\circ C$; for water, this is $1\,cal/g/^\circ C$.

Evaporation

The transformation of a substance from liquid to gas.

Heat of vaporization

The heat a liquid must absorb for $1\,g$ to be converted to gas.

Evaporative cooling

A process where the remaining surface of a liquid cools as it evaporates, helping to stabilize temperatures.

Solution

A liquid that is a completely homogeneous mixture of substances.

Solvent

The dissolving agent of a solution.

Solute

The substance that is dissolved in a solution.

Aqueous solution

A solution in which water is the solvent.

Hydration shell

A sphere of water molecules that surrounds each ion when an ionic compound is dissolved in water.

Hydrophilic

A substance that has an affinity for water.

Hydrophobic

A substance that does not have an affinity for water, such as oil molecules.

Molecular mass

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

Mole (mol)

A unit of measurement where $1\text{ mole} = 6.02 \times 10^{23}$ molecules.

Molarity (M)

The number of moles of solute per liter of solution.

Hydrogen ion ($H^+$)

A single proton with a charge of $+1$ that leaves its electron behind when a hydrogen atom in a hydrogen bond shifts between water molecules.

Hydroxide ion ($OH^-$)

The water molecule that lost a proton during dissociation, now carrying a charge of $-1$.

Hydronium ion ($H_3O^+$)

The water molecule that gained an extra proton during dissociation, often represented as $H^+$.

Acid

Any substance that increases the $H^+$ concentration of a solution.

Base

Any substance that reduces the $H^+$ concentration of a solution.

pH scale

A scale used to describe the acidity or basicity of a solution, defined as $pH = -\log[H^+]$.

Buffer

A substance that minimizes changes in concentrations of $H^+$ and $OH^-$ in a solution, usually containing a weak acid and its corresponding base.

Ocean acidification

The process where $CO_2$ dissolved in seawater forms carbonic acid, decreasing the pH of the ocean.

Calcification

The production of calcium carbonate ($CaCO_3$) by marine organisms, which is impaired by ocean acidification.