Standard Energy Change of Formation
The standard Gibbs free energy of formation of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of that substance from its component elements, at their standard states (the most stable form of the element at 25 degrees Celsius and 100 kilopascals). Its symbol is ΔfG˚.
All elements in their standard states (oxygen gas, graphite, etc.) have 0 standard Gibbs free energy change of formation, as there is no change involved.
- ΔrG = ΔrG˚ + RT ln Qr; Qr is the reaction quotient.
At equilibrium, ΔrG = 0 and Qr = K so the equation becomes ΔrG˚ = −RT ln K; K is the equilibrium constant.
Read more about this topic: Gibbs Free Energy
Famous quotes containing the words standard, energy, change and/or formation:
“[The Declaration of Independence] meant to set up a standard maxim for free society, which should be familiar to all, and revered by all; constantly looked to, constantly labored for, and even though never perfectly attained, constantly approximated, and thereby constantly spreading and deepening its influence, and augmenting the happiness and value of life to all people of all colors everywhere.”
—Abraham Lincoln (1809–1865)
“A government deriving its energy from the will of the society, and operating, by the reason of its measures, on the understanding and interest of the society ... is the government for which philosophy has been searching and humanity been fighting from the most remote ages ... which it is the glory of America to have invented, and her unrivalled happiness to possess.”
—James Madison (1751–1836)
“If someone were to prove to me—right this minute—that God, in all his luminousness, exists, it wouldn’t change a single aspect of my behavior.”
—Luis Buñuel (1900–1983)
“The moral virtues, then, are produced in us neither by nature nor against nature. Nature, indeed, prepares in us the ground for their reception, but their complete formation is the product of habit.”
—Aristotle (384–322 B.C.)