Chapter 20
spontaneous
A process that can occur without a continuous input of energy is a(n) _____ process.
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
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)
The different possible ways for arranging the particles of a system are called _____. The greater the number of these states, the _____ the entropy of the system.
Microstates, larger
In which of the following options does the first species of each pair have a greater standard entropy? Select all that apply.
A gas at 250°C vs. the same gas at 100°C A more complex substance vs. a simpler substance in the same phase if their molar masses are similar
Which of the following factors increase the likelihood that a reaction will be spontaneous? Select all that apply.
A gas is generated from a liquid. Energy is released in the form of heat. A liquid is generated from a solid.
In which of the following options does the first species of each pair have a greater standard entropy? Select all that apply. Multiple select question.
A more complex substance vs. a simpler substance in the same phase if their molar masses are similar A gas at 250°C vs. the same gas at 100°C
Which of the following statements correctly reflect the relationship between the spontaneity of a reaction and the sign of ΔH? Select all that apply
An endothermic process may be spontaneous under one set of conditions but nonspontaneous at a different temperature and pressure. It is possible for an exothermic process to be nonspontaneous.
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 first law of thermodynamics states that _____ is always conserved.
Energy
Which of the following statements correctly describe the general trends in standard entropy? Select all that apply.
For elements with two allotropic forms, the one that is more mobile will have a greater value for standard entropy. For two monatomic species, the one with the larger molar mass will have a higher standard entropy.
Which of the following options correctly reflect the relationships between ΔSsurr, ΔHsys, and T (at constant pressure so qsys = ΔHsys)? Select all that apply. Multiple select question.
If ΔHsys is negative, ΔSsurr will be positive. ΔSsurr is inversely proportional to temperature.
The combustion of glucose, represented by the equation C6H12O6 (s) + 6O2 (g) → 6CO2 (g) + 6H2O (g), is an exothermic reaction. Does this reaction cause an increase or decrease in entropy for the system and its surroundings?
Increase in ΔSsys Increase in ΔSsurr
As the temperature of a system increases, the entropy _____ due to a(n) _____ in the number of available energy states and thus a(n) _____ in the number of possible arrangements of molecules within those energy states. Multiple choice question.
Increase;increase;increase
What effect does increasing the temperature of a gas have on its entropy, and why? Select all that apply.
The entropy of a system increases as the temperature increases. As the temperature of a system is increased, all types of kinetic energies increase.
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?
The reaction is spontaneous at this temperature. ΔG = -131.1 kJ
H2CO3 (aq) → H2O (l) + CO2 (g) N2O4 (g) → 2NO2 (g)
Which of the following reactions are predicted to have a positive value for ΔSrxn? Select all that apply.
ΔG for a reaction is equal to the maximum amount of useful workBlank 1Blank 1 work , Correct Unavailable the system can do during a spontaneous reaction at constant temperature and pressure.
Work
Which of the following correctly describes the relationship between the free energy change, the reaction quotient, and the equilibrium constant? Multiple choice question.
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.
Under standard-state conditions, the equation ΔG = RT ln(QKQK) 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
A particular process results in a decrease in the entropy of the system. If this process is spontaneous, what must be true about the entropy change of the surroundings?
ΔSsurr > -ΔSsys
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. Multiple choice question.
More, products
Two unknown reactions (A and B) are analyzed. It is found that reaction A is exothermic, while reaction B is endothermic. Which of these reactions is spontaneous?
Spontaneity cannot be determined from the given information.
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) + 3232O2 (g); ΔG = 740.98 kJ
The free energy change must be more negative than -740.98 kJ.
Which of the following options correctly describe entropy? Select all that apply.
The greater the freedom of motion of particles in a system, the greater the entropy of the system. Entropy is a measure of the energy dispersal of a system.