Ch 20 smart book part 2
Calculate the free energy change for the reaction Cu2O (s) → Cu (s) + 12O2 (g) at 375 K if ΔH = 168 kJ/mol and ΔS = -9.63 J/K⋅mol.
+172 kJ/mol
In the expression ΔG = RT ln(QK), ΔG = when Q is equal to K, i.e., when QK = .
0 1
The molecular scene shows a gaseous equilibrium mixture at 460°C for the reaction of H2 (blue) and I2 (purple) to form HI according to the balanced equation H2 (g) + I2 (g) → 2HI (g). Each particle in the molecular scene represents 0.010 mol and the container volume is 1.0 L. Which statements correctly describe this system? Select all that apply.
Kc for the reaction = 50. ΔG° = -23.8 kJ/mol
Calculate the free energy change for the reaction Cu2O (s) → Cu (s) + 12O2 (g) at 375 K if ΔH = 168 kJ/mol and ΔS = -9.63 J/K⋅mol
+172 kJ/mol
Ksp for iron(III) hydroxide [Fe(OH)3] is equal to 1.1 x 10-36 at 25oC. Determine ΔGo (in kJ/mol) at 25oC for the reaction represented by the equation Fe(OH)3 (s) ⇌ Fe3+ (aq) + 3OH- (aq).
+205 kJ/mol
Calculate the standard free energy change for the reaction shown below. 2Fe2+ (aq) + H2O2 (aq) + 2H+ (aq) → 2H2O (l) + 2Fe3+ (aq); Eocell = 1.00 V, F = 96,500 J/V⋅mol
-193 kJ
A reaction taking place at 100oC has an entropy change of 200 J/K and an enthalpy change of -20 kJ. Which of the following expressions would be used to calculate ΔG under these conditions?
-20,000 - (373)(200)
Using the data provided in the table, calculate the equilibrium constant KP at 25oC for the reaction 2O3 (g) ⇌ 3O2 (g).
2.1 x 1057
The following reaction takes place at 25°C and has a standard cell potential equal to +0.47 V: Cu2+ (aq) + Pb (s) → Pb2+ (aq) + Cu (s) What is the equilibrium constant for this reaction?
7.9 × 1015
Since entropy is typically tabulated in units of / K and standard enthalpies are typically tabulated in units of / mol, it is usually necessary to perform a unit conversion when using the formula ΔG = ΔH - TΔS to calculate the Gibbs free energy.
J kJ
When a reaction is at equilibrium, the reaction quotient Q is always equal to and ΔG is equal to .
K 0
Under what conditions will the reaction of graphite shown below be spontaneous? C (s) + 2Cl2 (g) → CCl4 (g); ΔH° = -106.7 kJ
Spontaneous only at low T
Which of the following values must be known in order to calculate the change in Gibbs free energy using the Gibbs equation? Select all that apply.
T ΔSsys ΔHsys
If the reaction shown below is to be coupled to a second reaction in order to generate an overall spontaneous process, what must be true regarding this second reaction? Fe2O3 (s) → 2Fe (s) + 32 O2 (g); ΔG = 740.98 kJ
The free energy change must be more negative than -740.98 kJ.
As the reaction quotient Q increases, what is the effect on the spontaneity of the reaction?
The reaction becomes less spontaneous.
The molecular scene shows a gaseous equilibrium mixture at 298 K for the reaction of X into X2 according to the balanced equation 2X (g) → X2 (g). Each particle in the molecular scene represents 0.10 mol, and the container volume is 1.0 L. Which statements correctly describe this system? Select all that apply.
The reaction is nonspontaneous as written. Kc for the reaction = 0.80 ΔG° = 0.55 kJ/mol
Consider the chemical reaction 2SO3 (g) → O2 (g) + 2SO2 (g), for which ΔH° = +198.4 kJ and ΔS° = +187.9 J/K. Which of the following statements correctly describe the effect of temperature on the spontaneity of this reaction? Select all that apply.
The reaction will become more spontaneous as the temperature increases. The reaction is spontaneous only at higher temperatures.
In the human body, the oxidation of glucose produces sufficient free energy to drive the conversion of biomolecule ADP into ATP, a nonspontaneous process. This is an example of ______, where one step supplies enough free energy for another to occur.
coupling
The Gibbs energy change (symbolized by Δ) is a measure of the spontaneity of a process and of the useful energy available from it.
free G
If a given process proceeds spontaneously toward the products, the value of the reaction quotient Q is _____ the equilibrium constant K and ΔG for the reaction will be _____.
less than; negative
If a given reversible reaction has positive values for both ΔH and ΔS, the value of ΔG will become _____ negative as temperature increases and the formation of the _____ will be increasingly favored.
more; products
The larger the equilibrium constant K for a reaction, the more _____ the value of ΔGo and the more the _____ are favored at equilibrium.
negative; products
The standard free energy change for a reaction is the free energy change for the reaction under -state conditions, which assumes that all gases are at atm of pressure and all solutions have a concentration of M.
standard 1 1
ΔG for a reaction is equal to the maximum amount of useful the system can do during a spontaneous reaction at constant temperature and pressure.
work
ΔG is the maximum amount of useful _____ the system can possibly produce during a spontaneous process at constant T and P.
work
Consider the chemical reaction 2SO2 (g) + O2 (g) → 2SO3 (g), which has ΔH° = -198.4 kJ and ΔS° = -187.9 J/K. What is the value of ΔG°, and is the reaction spontaneous or nonspontaneous at 85°C?
ΔG = -131.1 kJ The reaction is spontaneous at this temperature.
Which of the following correctly describes the relationship between the free energy change, the reaction quotient, and the equilibrium constant?
ΔG = RT ln (QK)
Which of the following options correctly describe the Gibbs free energy change (ΔG) of a system? Select all that apply.
ΔG is a measure of the spontaneity of a process. The free energy change for a process is a measure of the useful work it can provide.
Which of the following is the correct form of the Gibbs equation for a process occurring at constant temperature?
ΔGsys = ΔHsys - TΔSsys
Under standard-state conditions, the equation ΔG = RT ln(QK) simplifies to which of the following?
ΔG° = -RT ln(K)
A reaction is found to be spontaneous only at high temperatures. Which of the following must be true? Select all that apply.
ΔHorxn > 0 ΔSorxn > 0
