Thermochemistry Lecture Notes

These flashcards cover key concepts related to thermochemistry, including energy definitions, energy types, thermodynamic laws, calorimetry, and enthalpy.

Energy

The ability to do work.

Work

A force acting over a distance.

Heat

The flow of energy caused by a difference in temperature.

Temperature

A numerical measure of hot and cold.

Joule (J)

The amount of energy needed to move a 1-kg mass a distance of 1 meter.

Calorie (cal)

The amount of energy needed to raise the temperature of one gram of water by 1°C.

Thermal Equilibrium

Heat flows from matter with high temperature to matter with low temperature until both objects reach the same temperature.

Kinetic Energy

Energy due to motion.

Potential Energy

Energy due to position or composition.

Thermal Energy

Energy associated with temperature.

Chemical Energy

Energy associated with positions of electrons and nuclei.

1st Law of Thermodynamics

The total amount of energy in the universe is constant; energy cannot be created or destroyed.

Internal Energy

The sum of the kinetic and potential energies of all the particles that compose the system.

Energy Exchange

Energy is exchanged between the system and surroundings through heat and work.

Heat Capacity

The quantity of heat absorbed or released when a substance experiences a temperature change of 1 degree Celsius.

Specific Heat Capacity

The amount of heat energy required to raise the temperature of one gram of a substance by 1°C.

Molar Heat Capacity

The amount of heat energy required to raise the temperature of one mole of a substance by 1°C.

Calorimetry

The measurement of the quantity of heat absorbed or released in a chemical reaction.

Enthalpy (H)

The sum of the internal energy of the system and the product of pressure and volume.

Exothermic Reactions

Reactions that release heat when ΔH is negative.

Endothermic Reactions

Reactions that absorb heat when ΔH is positive.

Hess's Law

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

Standard Enthalpy Change (ΔH°)

The enthalpy change when all reactants and products are in their standard states.