MYTUTOR SUBJECT ANSWERS

733 views

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

Helen S. A Level Chemistry tutor, GCSE Chemistry tutor, GCSE Maths tutor

2 years ago

Answered by Helen, who has applied to tutor A Level Chemistry with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

122 SUBJECT SPECIALISTS

£36 /hr

Steven A.

Degree: Bioscience (Masters) - Durham University

Subjects offered:Chemistry, Science+ 5 more

Chemistry
Science
Maths
Human Biology
English
-Personal Statements-

“Hey! I'm Steven, 18 years old and I'm studying Biochemistry at Durham University. I love tutoring people, to put it simply. At my college i was a tutor to a student in the year below me for chemistry and growing up with a younger sist...”

£24 /hr

Joshua T.

Degree: Chemistry PhD (Doctorate) - Bristol University

Subjects offered:Chemistry, Physics

Chemistry
Physics

“Chemistry PhD student at the University of Bristol, with a masters degree in chemistry from the University of Oxford. Available to teach Chemistry and Physics”

£22 /hr

George N.

Degree: Chemistry (Masters) - York University

Subjects offered:Chemistry, Physics

Chemistry
Physics

“20 year old second year chemistry student at the University of York. Drummer, guitarist, rugby player and radio host who has experience and a love for tutoring.”

About the author

£20 /hr

Helen S.

Degree: Chemistry (Masters) - Durham University

Subjects offered:Chemistry, Maths

Chemistry
Maths

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

MyTutor guarantee

You may also like...

Other A Level Chemistry questions

What's the difference between Aliphatic and Aromatic Molecules?

Explain why the second ionisation energy of boron is higher than the first ionisation energy of boron?

What is the structure of benzene?

What is chirality/optical isomerism?

View A Level Chemistry tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok