A Reaction That Is Spontaneous Is?
April 27th, 2009
a. has a + ∆G
b.occurs very rapidly
c.does not require enzyme catalysis in a cell
d.will decrease the entrophy of a system
e.is exergonic
AP Biology Question please help!!!
Entry Filed under: Thermochemistry
5 Comments Add your own
1. Chris | April 27th, 2009 at 11:00 pm
e
Because….
a) should be - delta G (Gibbs free energy)
b) speed depends on kinetics, nothing to do with spontaneity
c) not necessarily spontaneous
d) no reaction does this unless you add energy, thus it will not be spontaneous
e) means delta G < 0
2. Joe | April 27th, 2009 at 11:00 pm
That’s just a bad question.
A is wrong because spontaneous reactions at constant pressure have a negative delta G.
B is wrong because the spontaneity of a reaction says absolutely nothing about its rate.
C could be right, but it’s misleading. For example, the hydrolysis of a polypeptide is thermodynamically favored and spontaneous. But, without the presence of an enzyme or other catalyst, it will occur at an extremely slow rate
D is wrong. The entropy of the system can be positive or negative during a spontaneous reaction. The driving force could be enthalpy (as well as an increase in entropy outside of the system, not spontaneous process does not increase the total entropy of the universe).
E. Exergonic reactions can be either spontaneous or nonspontaneous depending on the entropy change associated with the reaction. The freezing of water is exergonic, but it’s only spontaneous at certain temperatures and pressures. Ice will not form at atmospheric pressure above 0 degrees celsius.
I would select C because it’s the only answer that is even the slightest bit correct.
3. Nick | April 27th, 2009 at 11:00 pm
spontaneous
4. forevers | April 27th, 2009 at 11:00 pm
C….good luck!
5. Jesus | April 27th, 2009 at 11:00 pm
b maybe
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