Chem - Thermochemistry Flashcards
Thermochemistry
The study of energy and its transformations
System
The part of the universe being observed
Internal energy
The sum of potential and kinetic energy of all particles present
A change in the energy of a system must be accompanied by
An equal and opposite change in energy of the surroundings
Heat (q)
Energy transferred as a result of differences in temperature between multiple objects
Work (w)
Energy transferred when an object is moved by force
Work of expansion
volume of the system increases when temperature is raised or chemical reaction results in a net increase in moles of gas; system expands and does work on surroundings, losing energy
Work of contraction
Volume of the system decreases when temperature is lowered or chemical reaction results in net decrease of moles of gas; system contracts and has work done on it by the surroundings, gaining energy
Exothermic
Releases heat; H is negative
Endothermic
Absorbs heat; H is positive
Specific Heat Capacity
The amount of heat required to change the temperature of 1g of a substance by 1K
Latent Heat
the energy absorbed or released during a change in state
Hess’s Law
The enthalpy change of an overall process is the sum of the enthalpy changes of its individual steps
Standard state
The most abundant and stable state of an element
Formation equation
Chemical equation that shows the formation of a substance from the elements it is composed of
