Chem Chapter 7: Thermochemistry Overview

thermochemistry

The study of the relationships between chemical reactions and energy changes.

energy

The capacity to do work or transfer heat.

work

The result of a force acting through a distance.

kinetic energy

The energy due to the motion of an object.

potential energy

The energy associated with the position or composition of an object.

law of conservation of energy

The principle that energy cannot be created or destroyed, only converted from one form to another.

system

The part of the universe being studied, separated by boundaries from its surroundings.

surroundings

Everything outside the system that can exchange energy with it.

heat

Energy that is transferred from one body to another due to a temperature difference.

first law of thermodynamics

The law stating that the total energy of an isolated system is constant, energy can neither be created nor destroyed.

enthalpy

A measure of the total energy of a thermodynamic system, often represented by H.

exothermic reaction

A chemical reaction that releases heat to the surroundings.

endothermic reaction

A chemical reaction that absorbs heat from the surroundings.

calorimetry

The measurement of heat changes in chemical reactions.

coffee-cup calorimeter

A device used to measure the heat change in reactions occurring at constant pressure.

bomb calorimeter

A device for measuring energy changes at constant volume, often used in combustion reactions.

Hess's law

A principle stating that the total enthalpy change for a chemical reaction is the sum of the enthalpy changes for the individual steps.

standard enthalpy of formation

The change in enthalpy when one mole of a compound forms from its elements in their standard states.

specific heat capacity

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

pressure-volume work

Work associated with the expansion of a gas against an external pressure.

thermal equilibrium

The condition in which two bodies in contact with each other reach the same temperature.

enthalpy change (ΔH)

The heat exchange at constant pressure; it represents the difference in enthalpy between products and reactants.

internal energy (E)

The total energy contained within a system, including kinetic and potential energies.

specific heat (Cs)

The amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius.

joule (J)

The SI unit of energy.

calorie (cal)

The amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius.

kilowatt-hour (kWh)

A unit of energy equivalent to 1,000 watts of power used for one hour.

molar heat capacity

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

thermal energy transfer

The process of transferring energy as heat between objects at different temperatures.