Chapter 3: Water and the Fitness of the Environment

A set of key vocabulary flashcards covering the emergent properties of water, solutions, concentration measurements, and acid-base chemistry based on the lecture transcript.

Polar Molecule

A molecule in which opposite ends have opposite charges, such as a water molecule with positive and negative regions.

Cohesion

when identical molecules stick to each other

Adhesion

The clinging of water to plant cell walls, which helps to counter gravity during water transport.

Surface Tension

A measure of how hard it is to break the surface of a liquid, related to cohesion.

Kinetic Energy

The energy of motion.

Heat

A measure of the total amount of kinetic energy due to molecular motion for a given body of matter, which depends on the matter's volume.

Temperature

A measure of the intensity of heat due to the average kinetic energy of molecules, regardless of volume.

Calorie ($\text{cal}$)

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

Specific Heat

The amount of heat that must be absorbed or lost for $1\,g$ of a substance to change its temperature by $1\,^\circ\text{C}$.

Evaporation

The transformation of a substance from a liquid to a gas.

Heat of Vaporization

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

Evaporative Cooling

The process in which the remaining surface of a liquid cools as it evaporates, helping stabilize temperatures in organisms and bodies of water.

Solution

A liquid that is a homogeneous mixture of two or more 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

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

Hydrophilic Substance

A substance that has an affinity for water. (loves water)

Colloid

A stable suspension of fine particles formed when molecules are so large that they do not dissolve in water.

Hydrophobic Substance

A substance that does not have an affinity for water. (hates water)

Molecular Mass

The sum of the masses of all the atoms in a single molecule, measured in Daltons ($\text{Da}$) or atomic mass units ($\text{u}$).

Avogadro's Number

The number of molecules in a mole ($\text{mol}$), equal to $6.02 \times 10^{23}$.

Molar Mass

The mass of $1\,\text{mole}$ of a given substance.

Molarity

The number of moles of solute per liter of solution, which is the unit of concentration most often used for aqueous solutions.

Hydronium Ion ($H_3O^+$)

A water molecule that has acquired an extra proton ($H^+$) from another water molecule.

Hydroxide Ion ($OH^-$)

A water molecule that has lost a proton ($H^+$).

Acid

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

Base

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

Buffer

A substance that minimizes changes in the concentrations of $H^+$ and $OH^-$ in a solution, typically consisting of an acid-base pair.