Critical nuclei size and activation energy for homogeneous nucleation

[@Bennethp]

Great explanation, thank you very much!

[@yigitcan824]

Hi professor I have a question here about driving force. Why does driving force increases as temperature differrence is increasing ? If we have large supercooling , for example, we have many nucleis, small crystals ,rapid nucleation rate.But for small supercooling we have opposites. I wonder why it is like that?

[@TaylorSparks]

Volumetric difference in free energy between the two phases is driving transformation. Surface energy resists transformation. The volumetric term is increasing as we cool further below the thermodynamic equilibrium temperature.

[@yigitcan824]

@@TaylorSparks Oh I see .One more thing , total free energy (Gt=Gv+Gs) must be lower than zero Gt

[@TaylorSparks]

@@yigitcan824 volumetric sign is negative, but surface energy sign is positive!

[@yigitcan824]

@@TaylorSparks Ups in the slide I'm looking at ,it's written like I wrote before with positive sign _deltaGt= deltaGv +deltaGs_

[@eduardoschiavon5652]

Great video as always! I was just a bit confused at 5:16, should I think of this delta_G* as an activation energy like the one that's needed for a Chemical Reaction to occur, or is it a similar, but different concept? I'm asking this because, from what I remember of Kinetics, a change in temperature doesn't change the activation energy of a Chemical Reaction.

[@TaylorSparks]

Yes, this is an activation energy. It's an energy barrier that has to be overcome. In this case, temperature definitely can change that activation energy.

[@eduardoschiavon5652]

@@TaylorSparks Ok, thank you!

[@kushalgupta2797]

Thank you it helped me in cheating my iit exam thank you🍾🥂🍻

[@TaylorSparks]

Cheating??? 🤨

[@mussieteklit6061]

thank you so much

[@liyajesus5388]

thank you, explain crystal growth