change in free energy equation

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Tiamaria
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change in free energy equation

Post by Tiamaria » Thu Jan 20, 2011 7:36 pm

Hello Everyone here is another question i am stuck on. its the same kind of thing that stumped me before.

2. For the reaction
furmate <----> malate

what is the change in free energy when one mole of furmate reacts to make one mole of malate under standard conditions?
K'eq = 02818

^G' = -(2.303)RT Log K'eq where K'eq = 0.2818

THE FIRST THING I GET STUCK ON IS HOW K'eq WENT FROM 02818 IN THE QUESTION, TO .2818 IN THE SOLVING PART OF THE QUESTION. HOWEVER, I JUST ACCEPTED IT AS A TYPO?? AND CONTINUED TO TRY TO FIGURE IT OUT.

^G = -(2.303)(1.987cal/mol K) (298 K) log 0.2818
^G = - (1364 cal/mol) log .02818

NOW HERE IS WHERE I GET STUCK. I DONT KNOW HOW TO GET RID OF THE "LOG"

the answer goes on to:
= -(1364cal/mol)(-.5501)
=750 cal / mol

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canalon
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Post by canalon » Thu Jan 20, 2011 11:48 pm

LOG is a mathematical operation. In this case it is the Decimal logarithm (sometimes abbreviated as Log10), not the natural logarithm (generally abbreviated as Ln).
It means that 10^(-0.5501)=0.2818
It is quite hard to calculate in your head, or even on paper, but most calculator (even google) will give you the correct value.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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