GenChem question help

[albitk05]

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Hey guys I am having difficulty understanding the solution to this question and where they got some of their reasonings from, a little help would be appreciated 🙂

"For reaction A ->B, if the entropy is increased and the temperature remains constant,______will be favored at equilibrium and (delta)G will be _____."
A. reactant A; positive
B. reactant A; negative
C. reactant B; postive
D. reactant B; negative
E. reactant A=reactant B; 0

So the answer is given as D, I guessed it right but here is the explanation:

"the equations related to this problem are (delta)G=(d)H-T(d)S=-2.3RTlogKeq. If the entropy is increased and the temperature remains constant, (d)H=0 and (d)H-T(d)S is equal to a negative number. Hence, (d)G is negative and Keq must be greater than 1 so that -2.3RTlogKeq remains a negative number.

(d) is delta if you didnt realize my laziness kick in
I think the biggest problem for me is how they know that (d)H=0. anyway the help is greatly appreciated!

 

[LSDP]

...Edit my explanation is wrong. Why dH is 0?

I just think dH is related to heat and since no heat was added or remove therefore dH is 0.

 

[albitk05]

so if i knew that temperature and (d)H are related then thats how i get (d)=0. after that its pretty straight forward.

well thanks for the response. yea it is a harder one. this was from a Barrons exam fyi.

 

[snehagodi]

Hey guys do we need to memorize the periodic table completely with its mass numbers and atomic numbers ????

 

[tayloreve]

Hey guys do we need to memorize the periodic table completely with its mass numbers and atomic numbers ????

theres a periodic table you can use on the computer

 

[Kobebucsfan]

Hey guys do we need to memorize the periodic table completely with its mass numbers and atomic numbers ????

yes

 

[jhc83]

yes

I have my DAT tomorrow, and this just made my day. haha

 

[Troyvdg]

as stated above, dH=q at 1atm. with no temp change, no change in heat so dH=q=0

 

[Josh779]

DG=DH - TDS
If DH=0...and DS=(+)

DG=0 - T(+) OR DG=(-)

Since delta G is negative, products are favored over reactants. So we get for of B (the products) than A (the reactants).

Edit: lol I didn't notice you already posted that equation. Oh well lol