SME
Grade 10 Science
Entropy, free energy and spontaneity
The main lesson, then each kind of problem it solves.
Entropy, free energy and spontaneity
Main lesson
The temperature where it turns spontaneous
Use this for “Above what temperature is a reaction with ΔH = 60 kJ/mol and ΔS = 150 J/(mol·K) spontaneous?”
ΔS° from a table, then ΔG°
Use this for “The products’ standard entropies add to 214 J/(mol·K) and the reactants’ to 188; ΔH° = −50 kJ/mol. What are ΔS° and ΔG° at 298 K?”
Does entropy go up or down?
Use this for “Predict the sign of ΔS when a gas forms from a solid.”
When is it spontaneous?
Use this for “A reaction has ΔH > 0 and ΔS > 0. When is it spontaneous?”