Gibbs free energy and spontaneity
At constant temperature and pressure, ΔG helps determine the thermodynamically favorable direction of a transformation.
Start with the idea
At constant temperature and pressure, ΔG helps determine the thermodynamically favorable direction of a transformation.
A concrete example
ΔG < 0 indicates a thermodynamically favorable change under the stated conditions, not necessarily a fast reaction.
Mendeleev’s tip
Do not start with a formula. Identify what changes, what stays constant and which quantity you are trying to explain or calculate.
Go one step deeper
The relation ΔG = ΔH − TΔS shows why temperature, enthalpy and entropy must be considered together.
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?