Forward toward equilibrium:

Reverse toward equilibrium:

At equilibrium: ΔG = 0; Q = K

Escaping equilibrium:1) Coupled reactionsΔGcoupled < 0 drives reaction

2) Doing work on systemElectrochemistry, enzymes

First law

Second law

Reaction at constant pressure

Reaction at constant pressure

Working with ΔG

Calculate from tabular data

ΔG changes with concentration

⇒

⇒

(calculate ΔG from Q vs K)

ΔG and non-PV work

closedsystem⇒

(electrochemistry)

heat out

work on

work by

heat in

Things mix, expand, break down

Temperatures even out

Reactions reach equilibrium

Direction of chemical reaction

surrounding

(calculate ΔG° from K)

Glossary

G: Gibbs energy = H - TSwnPV: non-PV workH: Enthalpy …°: standardS: Entropy Δ…: change inR: Gas constant …f: of formation

1) Among other things, an ideal fuel for the control thrusters of a

space vehicle should decompose in a spontaneous exothermic

reaction when exposed to the appropriate catalyst. Evaluate the

following substances under standard state conditions as

suitable candidates for fuels.

2) Calculate ΔG° for each of the following reactions from the

equilibrium constant at the temperature given.

3) In glycolysis, the reaction of glucose (Glu) to form glucose-

6-phosphate (G6P) requires ATP to be present as described

by the following equation:

Glu + ATP ⟶ G6P + ADP ΔG º = −17 kJ/mol In this process, ATP becomes ADP summarized by the

following equation:

ATP ⟶ ADP ΔGº =−30 kJ/mol Determine the standard free energy change for the following

reaction, and explain why ATP is necessary to drive this

process:

Glu ⟶ G6P ΔGº = ?

4) What happens to ΔG (becomes more negative or more

positive) for the following chemical reactions when the

concentration (partial pressure) of oxygen is increased?

a. S(s)+O2(g)⟶SO2(g)

b. 2SO2(g)+O2(g)⟶SO3(g)

c. HgO(s)⟶Hg(l)+O2(g)

5) Starting from tabulated enthalpies and entropies of

formation, calculate ΔG° and the equilibrium constant K for

the ammonia synthesis from the elements at temperatures of

100 K, 300 K and 500 K.

6) What is the Gibbs free energy necessary to transport a

hydrogen ion from a solution of pH = 4 to a solution of

pH = 7? Did you expect a positive or a negative value

7) What is the Gibbs free energy for the hydrolysis of ATP

under physiological conditions. The concentration of ATP is

about 5 mM, and that of the products ADP and phosphate is

about 0.5 mM. (See Q3 for the standard Gibbs energy)

8) What is the equilibrium constant for the reaction inside a

1.5 V alkaline battery? In the reaction, two electrons are

transferred (z = 2).