Question

Hi, I have 2 questions.

1) Which of the following has the largest entropy?

A) B2H6

B) BF3

C) BCl3

D) B2F2

4) Which is necessary for a process to be spontaneous?

A) Delta Gsys = 0

B) Delta Ssurr < 0

C) Delta Suniv > 0

Answer 1

1) Which of the following has the largest entropy?

A) B2H6

B) BF3

C) BCl3

D) B2F2

the largest mass typically has higher entropy

from the list:

B--Cl3 must have the most entropy, sicne it has higher mass

Q4

In order to compare equilibirum vs. spontaneous/nonspontaneous reactions, we better use a criteria.

Recall that if dSuniverse > 0, this is spontaneous, if dSuniverse = 0, this is inequilbirium and if dSuniverse < 0 this is never possible.

Then, recall that

dSuniverse = dSsurroundings + dSsystem

dSsystem = Sproducts - Sreactants

dSsurroundings = Qsurroundings/T = -dHsystem/T

therefore

dSystem =  -dHsystem/T + dSsystem

If we multiply by -T

dGrxn = dHrxn - T*dSrxn

Now, analysis of dG value... which is the "free energy" available for a process to follow

if dG <0 , this will be spontaneous

choose

C --> dSuniverse = 0, accoridng to 2nd law of thermo