What is Gibbs Free Energy?

Gibbs free energy allows you to link together the two factors entropy and enthalpy, these factors together determine if a chemical reaction is spontaneous or not. For a reaction to be spontaneous then the change in free energy must be negative. The change in Gibbs free energy is calculated using: dG = dH - TdS dH = Enthalpy change,T = Temperature (K)dS = Change in Entropy.  As dG depends on the term TdS this means that as the temperature increases the effect that dS has becomes more and more important. This results in some reactions only being spontaneous if the temperature is within the correct range. Enthalpy Entropy Spontaneous? Positive Positive Only below a certain temperature Negative Positive Yes, at all temperatures Positive Negative No Negative Negative Only above certain temperatures There is also a critical temperature; this is the temperature at which the reaction changes from being spontaneous to not being spontaneous. At this temperature dG = 0, hence meaning that T= dH/dS

HS
Answered by Helen S. Chemistry tutor

7454 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

In the presence of ultraviolet radiation, cyclohexane reacts with bromine. A mixture of cyclic products are formed, including C6H11Br. Discuss each step of this reaction providing equations to show the mechanism.


Describe a simple way to distinguish between aqueous solutions of potassium nitrate (KNO3) and potassium sulfate (K2SO4) using one test tube reaction


What is the pressure of one mole of an ideal gas at 273 K and in a volume of 1m3


Why does propanol have a higher boiling point than propanone, propanal or methyl ethanoate?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences