Phosphofructokindase catalyzes the transfer of a phosphate group (from ATP) to f
ID: 1076031 • Letter: P
Question
Phosphofructokindase catalyzes the transfer of a phosphate group (from ATP) to fructose-6-phosphate to produced fructose-1,6-bisphosphate. the delta H value for this reaction is -9.5kJxmol^-1 and th delta G is -17.2kJxmol^-1. a. Is the reaction exothermic or endothermic? b. What is the value of delta S for the reaction? Does this reaction proceed with an increase or decrease in entropy? c. Which component makes a greater contribution to the free energy value- the delta H or delta S value? Comment on the significance of this observation.
Explanation / Answer
a) The reaction is exothermic, since Delta H of the reaction is less than zero which implies the heat is given out to the system
The reaction will be exothermic in nature
b)
Delta G = Delta H - T * Delta S
-17.2 kJ = -9.5kJ - T(Delta S)
Since temperature is not given in the problem, assuming 25C( standard room temperature)
Delta S = 7700/(273+25) = 25.838 J/K
Since the Delta S is positive, hence entropy of the system has been increased
c) The Delta H value makes a greater contribution for Delta G to be negative, since 9.5 > 7.7