BCH HW 3

Determine ∆G° for a reaction when ∆G = -146.2 kJ/mol and Q = 0.043 at 298 K. (R = 8.314 J/mol ･ K)

-138.4 kJ/mol The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. .Solve for ∆G° in the following equation :ΔG=ΔG°+RTlnQ

One hour of bicycle racing can require 500-900 kcal of energy, depending on the speed of the race, the terrain, and the weight of the racer. Tour de France riders must consume abnormal amounts of food to supply this energy. Food in the form of protein or carbohydrates produces 17.0 kJ of energy per gram consumed. How many kilograms of protein or carbohydrate must be consumed to provide the energy for 195 minutes of racing that requires 650.0 kcal/hr. (Recall 1 kcal = 4.184 kJ)

..520 kg

The association of a protein and a fragment of DNA has a ΔG°′ of -57 kJ/mol. What is the equilibrium constant at 25 °C for the formation of this complex?

1

How many calories are in 8201 J ? (1 cal = 4.184 J)

1960 cal

At what temperature, in K, does X(l) → X(g) occur spontaneously? ∆H° = 573 kJ/mol ∆S° = 1.64 kJ/mol*K

349 K ΔG°=ΔH°−TΔS°

What is K for a reaction if ∆G° =-187.1 kJ/mol at 25°C? (R = 8.314 J/mol ･ K)

6.26 × 10³² The following solution may contain one or more values that are different from the problem provided to you, however, the steps to solve the problem are the same. .Solve for K in the following equation:ΔG°=−RTlnK

How many Joules are there in 2221 calories? (1 cal = 4.184 J)

9250.8

The First Law of Thermodynamics tells us A) that the energy of the universe is always increasing. B) that the energy of the universe is a constant. C) that the energy for a chemical reaction is a constant. D) that a chemical reaction will always release energy.

B) that the energy of the universe is a constant.

Based upon the following reactions, what would be the ΔG°′ for the formation of ATP from phosphoenolpyruvate and ADP? ATP → ADP + Pi ΔG°′ = −31.5 kJ/mol phosphoenolpyruvate → pyruvate + Pi ΔG°′ = −62.2 kJ/mol

B) −30.7 kJ/mol

Which of the following does the change in the free energy of a reaction predict? A) the work done B) the speed C) the spontaneity D) the final temperature E) the heat released

C) the spontaneity C) the spontaneity

All are true about ΔG EXCEPT?

E) ΔG is negative for endergonic reactions.

What will the sign on ∆S be for the following reaction and why? 2 Mg (s) + O₂ (g) → 2 MgO (s)

Negative, because there are more moles of gas on the reactant side than the product side The sign of ∆S can be determined by comparing the number of moles of gas on the reactant and product side. Since the number of moles of gas is decreasing, entropy is decreasing, and thus is negative.

Which of the following reactions would have the most negative ∆S° value ?

The most negative change in entropy would indicate that there is less disorder at the end of the reaction. Option D goes from two moles of very disordered gases to one mole of highly ordered solid

Given the following reaction, what can be said about the equilibrium concentrations of the components of the reaction? (do not assume that concentrations began at standard conditions) pyruvate + NADH + H+ <=> lactate + NAD+ ΔG°′ = −25.2 kJ/mol

cannot determine

If ∆H > 0 and ∆S < 0, a reaction will be:

nonspontaneous

Living systems are:

open systems exchanging both energy and matter with their surroundings.

"High-energy" compounds exhibit large negative free energy of hydrolysis and include all EXCEPT: phosphate esters enol phosphates acyl phosphates guanidine phosphates thioesters

phosphate esters.

A reaction which is endothermic and has an overall increase in entropy is ______

spontaneous only at high T Spontaneity is determined by the free energy. When ΔGΔG is negative, it is spontaneous. ΔG=ΔH−TΔSΔG=ΔH−TΔS The problem indicates that the ΔSΔS is positive. If the reaction is endothermic, this means that the ΔHΔH is positive. The only way for ΔGΔG to be negative is if the temperatures are very high.

Biochemists define the group transfer potential as the ____ that occurs upon hydrolysis (i.e., transfer of the particular group to water)

∆G

Predict how ∆G changes with increasing temperature for the reaction A(g) + B(g) → C(g). ΔH°= -201 kJ/mol ΔS = - 189.2 J/mol*K

∆G becomes less negative and the reaction becomes less spontaneous

A reaction will be spontaneous at all temperatures if _____

∆H is negative and ∆S is positive The free energy can be calculated using this formula. ΔG=ΔH−TΔSΔG=ΔH−TΔS A reaction will be spontaneous at all temperatures if ∆H is negative and ∆S is positive.