Gibbs' Free Energy

Question	Answer
What happens when a reaction is energetically feasible?	Spontaneous reaction
What is free energy change?	ΔG The overall change in energy during a chemical reaction
What is ΔG made up of?	The enthalpy change ΔH - heat transfer between chemical system and surroundings The entropy change at the temperature of the reaction TΔS This is the dispersal of energy within the chemical system itself
How is the relationship between these two described?	GIBBS' EQUATION ΔG=ΔH-TΔS
What is needed for a reaction to be feasible?	ΔG<0 So reaction is exergonic
What are the units of ΔH and ΔS?	kJmol-1 JK-1mol-1 ΔS is much smaller, we change it to kjmol-1 by dividing by 1000 (question page 366)
What conditions support feasibility?	When ΔH is negative (so less energy out of system) When ΔS is positive, T increases ΔS significantly because TΔS
What is ΔG at minimum temperature?	ΔG=0
How would you rearrange the Gibbs' equation to calculate the minimum temperature?	ΔH-TΔS=0 T=ΔH/ΔS (Convert K to C if applicable.)
How can endothermic reactions take place at RTP?	Some ionic compounds dissolve in water at RTP, cooling down the water, as long as ΔG<0 it'll be feasible
What are the limitations of predictions for feasibility?	Although ΔG may indicate thermodynamic feasibility, it doesn't take into account kinetics or the rate of a reaction i.e. H2O2, has a very high activation energy so a slow reation rate.

Resource summary

	Created by J yadonknow over 6 years ago