Thermochemistry and Intermolecular Forces

These flashcards cover the essential terms and concepts from the lecture on thermochemistry and intermolecular forces.

Thermochemistry

The study of heat (q) energy changes in chemical reactions and physical transformations.

Concerned with enthalpy (H)

Thermodynamics

The study of energy and the conversion between types of energy

Concerned with enthalpy, entropy(s), Gibbs free energy (G)

Enthalpy (H)

A measure of the total energy of a thermodynamic system, reflecting internal energy and the energy required to displace the environment.

Entropy (S)

A measure of the disorder or randomness in a system.

System

The chemicals involved in a reaction

Open system

A system that can exchange both energy and matter with its surroundings.

Closed system

A system that can exchange energy but not matter with its surroundings.

Isolated system

A system that cannot exchange either energy or matter with its surroundings.

Surroundings

Everything else (the container, water bath, atmosphere, the universe, etc.)

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

Internal Energy (U)

The total capacity of a system to do work, encompassing both kinetic and potential energy of particles.

Heat (q)

The form of energy transferred between bodies or systems due to a temperature difference.

Specific Heat Capacity (Cp)

The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.

Molar Heat Capacity (Cp,n)

The amount of heat required to raise the temperature of one mole of a substance by one degree Kelvin (or Celsius) at constant pressure.

Exothermic reaction

A reaction that releases heat to its surroundings.

Endothermic reaction

A reaction that absorbs heat from its surroundings.

Calorimetry

The measure of the amount of heat absorbed or released during a chemical reaction or physical process.

Hess's Law

The total enthalpy change for a reaction is the sum of the enthalpy changes for the individual steps of the reaction.

Intermolecular Forces (IMF)

Forces of attraction or repulsion between neighboring particles (molecules) that affect the physical properties of substances.

Dispersion Forces

Weak, temporary forces generated by temporary alignments of electrons within atoms.

Dipole-Dipole interactions

Attractive forces between polar molecules that arise from the attraction of positive and negative dipoles.

Hydrogen Bonds

Strong dipole-dipole forces that occur between hydrogen and electronegative atoms such as nitrogen, oxygen, or fluorine.

Viscosity

A measure of a liquid's resistance to flow and deformation.

Surface Tension

The amount of energy required to increase the surface area of a liquid.

Vapor Pressure

The pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature.