Enthalpy change

Question

In gluconeogenesis, glucose can be produced by reaction of pyruvic acid and glycerol. Upon consideration of the simplified version of this reaction, as shown below, and making use of the data in the table below, answer the following questions.

Compound

Δ​​fH​​ ​​ / kJ mol-​​ 1

Pyruvic acid

-582.1

Glycerol

-903.5

Glucose

-1273.3

(a) Calculate the enthalpy change for this reaction.

B) Calculate the free energy of reaction at 37 °C taking into account the entropy change: ∆S = -100 J mol-​ 1​. Recall that: ∆G = ∆H – T∆S

c) If 30 kJ mol-​ 1​ are released upon hydrolysis of ATP into ADP and Pi, how many moles of ATP are either produced or consumed in gluconeogenesis according to the reaction above?

Answer 1

Pyruvic acid + glycerol ==> glucose

∆Hrxn = (-1273.3) - (-582.1 + -903.5) = -1273.3 - (-1485.6) = 212.3 kJ/mole

∆G = ∆H- T∆S

∆G = 212.3 kJ/mol - (310K)(-0.100 kJ/K-mole) = 212.3 kJ/mole - (-31.0 kJ/mole)

∆G = 243.3 kJ/mole

(NOTE: You provided incorrect units for ∆S as it should contain a Kelvin unit, i.e. JK^-1mol^-1. Also note the change for ∆S from -100 J to -0.100 kJ to be constant with units of ∆H)

212.3 kJ/mole x 1 mol ATP/30 kJ = 7 moles ATP CONSUMED