This

**preview**shows half of the first page. to view the full**3 pages of the document.**LECTURE

13

Slide No. Notes

14 -nothing to do with rate

-spontaneous reaction can be slow or fast

-for instance, diamond to graphite is a very slow yet spontaneous

reaction

-if the forward reaction is spontaneous, the reverse is non-

spontaneous

15 - delta H is not enough to determine spontaneity

16 -S is a measure of disorder

-Entropy goes from localized to dispersion for spontaneous reactions

17 -gas particles are very spread out

-whereas solid particles are in ordered structures

18 -Ans1: B

-Ans2: A

-Ans3: B

-Ans4: A

-Second question:

-A) A2 (gas) + 2B (gas) -> 2AB (gas)

-B) negative S

19 -imagine two coins

-combinations of results are only HH; HT; TH; TT

-therefore 2 to the power of 2 is four

-imagine three coins

-combinations of results can be HHH; TTT; HHT; HTH; THT; TTH;

THH; HTT

-therefore 2 to the power of 3, which is 8

20 -solids vibrate faster, therefore higher entropy

-at BP, big jump in entropy because gas formed, particles very

spread out

-recall that at phase changes, the temperature does NOT change

21 -more entropy in drop of water than a bucket because entropy is an

extensive property

-Delta S = S of CaO plus S of CO2 subtract S of CaCO3 =

1mol(39.7J/Kmol) + 1mol times 213.6J/Kmol – 1 mol times

92.9J/molK = 160J/K

-This answer was expected to be positive so check!

22 -spontaneous – exogonic

-non-spontaneous – endogonic

-in Gibbs, surr incorporated by delta H of system

23 -note that the second sign is for delta S only, not the whole second

term including T

-negative H, positive S – negative G therefore reaction spontaneous

www.notesolution.com

###### You're Reading a Preview

Unlock to view full version