MYTUTOR SUBJECT ANSWERS

538 views

What is Gibbs free energy? How is it useful?

The Gibbs free energy of a process is a measure of how readily that process will proceed on its own - a negative value means that the reaction is spontaneous, a positive value means that it is not, and a value of or very close to zero means that it's an equilibrium process.
 

It's equation is: G = H - TS
Where G is the Gibbs energy, H is the enthalpy change, T is the temperature that the process is at, and S is the entropy change.


Temperature here is in Kelvin, and a classic trick is to give you the temperature in celsius so you have to remember to account for it by adding 273.
Another easy pitfall is that since the entropy S is so much smaller than the enthalpy H, it will be in J K-1 Mol-1 - and H will be in kJ K-1 Mol-1​. So you need to put both values in the same units. Always remember to check that your units 'add up' correctly - this is just as important as your numbers.

Typically a question will ask you to find the enthalpy change, or entropy change of a reaction, then give you the value you don't have and ask you to comment on how likely the reaction is to occur through calculating this Gibbs energy. These questions are, when it comes down to it, just a bit of arithmetic. 

Murdo M. A Level Maths tutor, A Level Chemistry tutor

2 years ago

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


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

94 SUBJECT SPECIALISTS

£22 /hr

Josh M.

Degree: Biological Natural Sciences (Bachelors) - Cambridge University

Subjects offered:Chemistry, Physics+ 3 more

Chemistry
Physics
Maths
Biology
-Oxbridge Preparation-

“Who am I? I'm currently studying Natural Sciences in my third year at Cambridge University, with a focus on Neuroscience. Science is my passion, I've loved it at every level I've studied it, and a desire to pass on my passion is part ...”

£24 /hr

Julia M.

Degree: Sustainable Agriculture and Food Security (Masters) - Edinburgh University

Subjects offered:Chemistry, Maths+ 1 more

Chemistry
Maths
Biology

“Enthusiastic friendly tutor looking for curious and ambitious students for fun and relaxed lessons”

PremiumLorenzo C. GCSE Biology tutor, A Level Biology tutor, GCSE Chemistry ...
£26 /hr

Lorenzo C.

Degree: Biomedical Sciences with Honours in Infectious Diseases (Bachelors) - Edinburgh University

Subjects offered:Chemistry, Physics+ 1 more

Chemistry
Physics
Biology

“5th in the World at International A-Level Biology Over two years experience in tutoring!”

About the author

£20 /hr

Murdo M.

Degree: Natural Sciences (Masters) - Durham University

Subjects offered:Chemistry, Physics+ 1 more

Chemistry
Physics
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 is entropy and how is it used in chemistry?

Describe the trend in the reactivity of group 2 elements with chlorine as you descend down the group.

Without a catalyst, an alkene will react with bromine while benzene will not. Why is this?

How do I calculate the Gibbs free energy change for a reaction when given the entropy change, enthalpy change and the reaction conditions>

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