General Chemistry Chapter 12: Solutions

Comprehensive vocabulary list covering concepts of solution chemistry, concentration units, solubility factors, colligative properties, and distillation based on the lecture notes.

Solutions

Homogeneous mixtures of two or more pure substances where the solute is dispersed uniformly throughout the solvent.

Solute

The substance in a solution that dissolves.

Solvent

The major component of a solution.

Concentration

The amount of solute that is present in a solution.

Dilute

A term describing a solution that contains a small amount of solute.

Concentrated

A term describing a solution that contains a large amount of solute.

Saturated solution

A solution that contains the maximum amount of dissolved solute.

Mass percent ($m/m$)

$$\frac{\text{mass of solute}}{\text{mass of solution}} \times 100\%$$

Volume percent ($v/v$)

$$\frac{\text{volume of solute}}{\text{volume of solution}} \times 100\%$$

Mass/volume percent ($m/v$)

$$\frac{\text{mass of solute}}{\text{volume of solution}} \times 100\%$$

Parts per million (ppm)

$\frac{\text{mass of solute}}{\text{mass of solution}} \times 10^6$; for water at $4\,^{\circ}\text{C}$, $1\,\text{ppm} = 1\,\text{mg/kg} = 1\,\text{mg/L}$.

Parts per billion (ppb)

$\frac{\text{mass of solute}}{\text{mass of solution}} \times 10^9$; for water at $4\,^{\circ}\text{C}$, $1\,\text{ppb} = 1\,\mu\text{g/kg} = 1\,\mu\text{g/L}$.

Molarity ($M$)

$\frac{\text{moles solute}}{\text{liter solution}}$; this value varies with temperature because volume changes.

Molality ($m$)

$\frac{\text{moles solute}}{\text{kg solvent}}$; this value does not vary with temperature because mass does not change.

Mole fraction ($\chi$)

The number of moles of one component in a mixture divided by the total number of moles present.

Dilution

The addition of solvent which decreases the concentration of the solute; characterized by the equation $M_1V_1 = M_2V_2$.

Electrolytes

Compounds that produce ions in solution, such as ionic compounds and acids.

Nonelectrolytes

Compounds that do not produce ions in solution, typically most covalent compounds.

Entropy

A tendency toward disorder or mixing that determines whether a change happens spontaneously.

Henry’s Law

An equation relating gas solubility to pressure: $S_{gas} = k_H P_{gas}$.

Van’t Hoff Factor ($i$)

The ratio of the number of particles that actually form in a solution to the number of particles per formula unit if complete dissociation occurs.

Colligative Properties

Properties that depend on the number of particles in a solution, not on the type of particle, including osmotic pressure, freezing point depression, and boiling point elevation.

Osmotic Pressure ($\Pi$)

The pressure calculated by $\Pi = iMRT$, where water flows toward the higher $\Pi$ value.

Freezing Point Depression ($\Delta T_f$)

The phenomenon where the presence of solute lowers the freezing point of a liquid, calculated as $\Delta T_f = imK_f$.

Boiling Point Elevation ($\Delta T_b$)

The phenomenon where the presence of solute raises the boiling point of a liquid because a higher temperature is required to reach atmospheric pressure, calculated as $\Delta T_b = imK_b$.

Raoult's Law

Relates the vapor pressure of a solution with a nonvolatile solute to the mole fraction of the solvent: $P_{soln} = (\chi_{solvent})(P_{solvent}^o)$.

Fractional distillation

A process using a tall column where vapors condense and re-evaporate, enriching the vapors with the more volatile component at each sequence.

Colloids

Suspensions of particles larger than individual ions or molecules, but too small to be settled out by gravity.