General Chemistry: Colligative Properties, Solutions, and Thermochemistry

Vocabulary terms covering colligative property formulas, solution preparation techniques, and thermodynamics principles from the lecture notes.

Colligative Properties

Properties that depend mainly on how many solute particles are present, rather than what those particles are called.

Boiling-point elevation equation

$$\Delta T_b = i K_b m$$

Freezing-point depression equation

$$\Delta T_f = i K_f m$$

Heat transfer equation

q = mc\text{\Delta}T where heat depends on mass, specific heat, and temperature change.

First law of thermodynamics equation

$\Delta U = q + w$ where internal energy changes through heat and work.

Molality (m)

$$m = \frac{\text{mol solute}}{\text{kg solvent}}$$

Kb for water

$$0.512\,^{\circ}\text{C}/m$$

Kf for water

$$1.86\,^{\circ}\text{C}/m$$

Van\u2019t Hoff factor (i)

The particle count representing the number of dissolved particles in a solution.

Nonelectrolyte

A substance that remains as whole molecules in water with a typical $i = 1$, such as glucose, sucrose, or urea.

Electrolyte

A substance that forms ions in solution with a typical $i$ of $2$ or more, such as $NaCl$, $KBr$, or $CaCl_2$.

Volumetric flask

Equipment used for an exact final volume because it has one precise calibration mark.

Meniscus

The curve of the liquid surface that must be read at the bottom at eye level to prevent parallax error.

Quantitative Transfer

The process of rinsing a beaker into a volumetric flask to ensure all dissolved solute is transferred.

Positive q

Indicates that the system absorbs heat and energy enters the system.

Negative q

Indicates that the system releases heat and energy leaves the system.

Positive w

Indicates work is done on the system and surroundings add energy.

Negative w

Indicates work is done by the system and the system transfers energy out.

Endothermic process

A process where heat flows into the system, $\Delta H$ is positive, and products are higher in enthalpy.

Exothermic process

A process where heat flows out of the system, $\Delta H$ is negative, and products are lower in enthalpy.

Hess\u2019s Law

The principle stating that the total enthalpy change depends only on the initial and final states.