CHE 1111 Unit 3 Exam Study Guide

Comprehensive vocabulary flashcards covering the key terms listed for CHE 1111 Unit 3 Exam Study Guide (Textbook Sections 5.1–5.6, 6.1–6.6, and 7.1–7.3).

Gas

A state of matter that has no definite shape or volume, expanding uniformly to completely fill its container.

Liquid

A state of matter that has a definite volume but no fixed shape, taking the shape of the container it occupies.

Solid

A state of matter characterized by a definite shape and a definite volume, with constituent particles closely packed in fixed positions.

Pressure

The force applied perpendicular to the surface of an object divided by the area over which that force is distributed ($P = \frac{F}{A}$).

Ideal Gas

A hypothetical gas whose particles occupy negligible volume and experience no intermolecular attractive or repulsive forces, perfectly obeying the ideal gas equation.

Boyle's Law

A gas law stating that at constant temperature and fixed amount of gas, the volume is inversely proportional to its pressure ($P_1V_1 = P_2V_2$).

Charles's Law

A gas law stating that at constant pressure and fixed amount of gas, the volume is directly proportional to its absolute temperature in kelvins ($\frac{V_1}{T_1} = \frac{V_2}{T_2}$).

Avogadro's Law

A gas law stating that equal volumes of gases at the same temperature and pressure contain equal numbers of moles ($\frac{V_1}{n_1} = \frac{V_2}{n_2}$).

Dalton's Law

The law stating that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual constituent gases.

Combined Gas Law

A gas law combining Boyle's, Charles's, and Gay-Lussac's laws, relating pressure, volume, and absolute temperature for a fixed amount of gas ($\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$).

Ideal Gas Law

The equation of state of a hypothetical ideal gas, expressed as $PV = nRT$.

Partial Pressure

The pressure that a single gas in a mixture would exert if it alone occupied the entire volume of the container at the same temperature.

Vapor Pressure

The pressure exerted by a vapor in thermodynamic equilibrium with its condensed phase (liquid or solid) at a specific temperature.

Universal Gas Constant

The proportionality constant ($R$) in the ideal gas equation, equal to approximately $8.314\,J\,mol^{-1}\,K^{-1}$.

Kinetic Molecular Theory

A model describing gas behavior as collections of particles in constant, random motion undergoing perfectly elastic collisions, possessing negligible volume, and having no attractive or repulsive intermolecular forces.

Effusion

The process by which gas molecules escape from a container into an evacuated space through a tiny pinhole without colliding with one another.

Diffusion

The gradual spreading and mixing of particles of one substance through another as a result of random thermal motion.

Potential energy

The energy stored in an object or system due to its position, state, or chemical composition.

Kinetic energy

The energy an object possesses due to its motion, defined by $E_k = \frac{1}{2}mv^2$.

Work

The energy transferred when an applied force moves an object across a distance, commonly represented in chemical systems as pressure-volume work ($w = -P\Delta V$).

Heat

The transfer of thermal energy between two bodies of differing temperatures that flows spontaneously from the warmer object to the cooler object.

State Function

A thermodynamic property whose value depends only on the current state of the system, independent of the path or process taken to achieve that state.

System and Surrounding

The specific part of the universe selected for thermodynamic study (system), and everything else in the universe outside of that designated part (surroundings).

Enthalpy

A thermodynamic quantity equal to the internal energy of a system plus the product of its pressure and volume ($H = E + PV$).

Endothermic

A process or chemical reaction that absorbs heat from its surroundings, resulting in a positive change in enthalpy ($\Delta H > 0$).

Exothermic

A process or chemical reaction that releases heat to its surroundings, resulting in a negative change in enthalpy ($\Delta H < 0$).

Specific Heat Capacity

The quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius (or one kelvin).

Heat Capacity

The amount of heat required to raise the temperature of a specified quantity of a substance by one degree Celsius (or one kelvin).

Calorimetry

The experimental technique used to measure heat changes and thermal energy transfers during chemical reactions or physical processes.

Enthalpy of reaction

The net enthalpy change ($\Delta H_{\text{rxn}}$) that occurs during a chemical reaction, equal to the total enthalpy of the products minus the total enthalpy of the reactants.

Hess's law

A principle stating that if a reaction can be expressed as the sum of multiple steps, the total enthalpy change of the overall reaction is the sum of the enthalpy changes of those individual steps.

Standard States

The agreed-upon reference state of a pure substance at a standard pressure of $1\,\text{bar}$ (or $1\,\text{atm}$) and a specified temperature (typically $298.15\,K$).

Standard enthalpy of Formation

The enthalpy change ($\Delta H_f^\circ$) that accompanies the formation of one mole of a compound in its standard state from its constituent elements in their standard states.

electromagnetic radiation

A form of energy consisting of perpendicular, oscillating electric and magnetic fields that travel through space at the speed of light.

frequency

The number of complete wave cycles that pass a given point per unit time, denoted by $\nu$ and measured in hertz ($\text{Hz}$ or $\text{s}^{-1}$).

wavelength

The distance between consecutive identical crests or troughs of a wave, denoted by $\lambda$.

speed of light

The constant speed at which all electromagnetic radiation travels in a vacuum, represented by $c$ and equal to approximately $3.00 \times 10^8\,m\,s^{-1}$.

electromagnetic spectrum

The continuous range of all types of electromagnetic radiation organized by frequency and wavelength, ranging from radio waves to gamma rays.

photon

A discrete, quantized packet of electromagnetic energy with energy directly proportional to its frequency ($E = h\nu$).

photoelectric effect

The phenomenon in which electrons are ejected from the surface of a material when exposed to light of frequency exceeding a certain threshold.

ground state

The lowest, most stable allowable electronic energy level of an atom, molecule, or ion.

excited state

Any allowable electronic energy level of an atom, molecule, or ion that is higher in energy than its ground state.

line spectrum

A spectrum exhibiting discrete, distinct wavelengths of light emitted or absorbed by an element, rather than a continuous band of colors.

emission spectrum

The spectrum of wavelengths emitted by atoms or molecules as they undergo transitions from higher energy states to lower energy states.

absorption spectrum

A spectrum showing dark lines or bands corresponding to specific wavelengths of electromagnetic radiation absorbed by a substance from a continuous source.

wave-particle duality

The quantum physical property wherein matter and light exhibit behaviors characteristic of both continuous waves and discrete particles.