ch 18 Flashcards
The Ksp of silver bromide is 5.4 × 10−13 at 298 K.
AgBr(s) Ag+(aq) + Br−(aq)
What is ΔrG°? (R = 8.314 J/K⋅mol)
e.
Estimate the boiling point of ethanol, C2H5OH, using the given the following thermodynamic parameters.
d.
Calculate the enthalpy of vaporization of water at its normal boiling point. ΔS° [H2O()] = 69.9 J/K⋅mol and ΔS° [H2O(g)] = 188.8 J/K⋅mol.
44.35 kJ/mol
When a real gas is compressed from low pressure to high pressure, its temperature increases. Which of the following is true for ΔH and ΔS?
a.
For any process, the change in entropy of the universe equals the sum of the entropy changes for the system and for the ________.
surroundings
Calculate the standard entropy change for the following reaction:
2 SO2(g) + O2(g) → 2 SO3(g)
Given: S°[SO2(g)] = 248.2 J/K⋅mol, S°[O2(g)] = 205.1 J/K⋅mol, and S°[SO3(g)] = 256.8 J/K⋅mol.
c.
Which of the following is true of a reaction that is product-favored?
a.
Which of the following is the second law of thermodynamics?
a.
Which of the following relationships is not true?
d.
Given the following data:
S(g) + O2(g) → SO2(g) ΔrG° = –300.1 kJ/mol-rxn
2 S(g) + 3 O2(g) → 2 SO3(g) ΔrG° = –742.1 kJ/mol-rxn
Calculate ΔfG° for the reaction below.
SO2(g) + 1/2 O2(g) → SO3(g)
b.
A reaction is said to be under thermodynamic control when _____.
a.
Hydrogen gas is prepared by electrolysis of water according to the reaction below.
2 H2O() → 2 H2(g) + O2(g)
Predict the signs of ΔrH and ΔrS.
a.
Using the given data, determine ΔrG° at 298 K for the precipitation reaction below.
Ag+(aq) +Br−(aq) → AgBr(s)
Substance ΔfG°(kJ/mol) at 298 K
Br−(aq)
–104.0
Ag+(aq)
77.12
AgBr(s)
–96.9
not c. or d. or .b
Given the following and that R = 8.314 J/K ⋅mol, determine the equilibrium constant, K, at 298K for the following reaction:
AgBr(s) → Ag+(aq) + Br−(aq)
Substance ΔfG°(kJ/mol) at 298 K
Br−(aq)
–104.0
Ag+(aq)
77.12
AgBr(s)
snot
–96.9
a.
Which of the following statements concerning entropy change is/are true?
1. For a reversible process, .
2. For a spontaneous process, .
3. For a reversible process, such as a phase change, ΔS = qrev/T .
d.
For a certain reversible process, q = 88.06 kJ at 29.4°C. Which of the following is the ΔS for the process?
b.
Arrange the following reactions in order of increasing ΔrS° value:
1. H2(g) + F2(g) → 2HF(g)
2. NH4NO3(s) → N2O(g) + 2H2O(l)
3. (NH4)2Cr2O7(s) → Cr2O3(s) + 4H2O(l) + N2(g)
not c
For the reaction Br2(l) → 2Br(g), _____.
a.
If a chemical reaction occurs in a direction that has a positive change in entropy, then _____.
e.
What is the equilibrium constant for the reaction below at 298 K?
2C(s) + 3H2(g) → C2H6(g)
Given: ΔrH° = –84.68 kJ; ΔrS° = –173.8 J/K at 298 K. (R = 8.314 J/K⋅mol)
a.
The change in entropy for any process is not dependent upon the pathway by which the process occurs. In other words, the change in entropy for any process is a(n) _____ function.
state
In which of the following reactions is ΔrS° expected to be positive?
e.
For a chemical reaction, if ΔrG° = 0, then _____.
e.
While diluting concentrated sulfuric acid with water, the temperature of the solution increases rapidly. What are the signs of ΔrH, ΔrS, and ΔrG for the process?
a.
What is the S0 for ozone if the standard entropy change for the reaction below is 411 J/K⋅mol-rxn and S0[O2(g)] = 205 J/K⋅mol.
c.
Which of the following changes lead to a decrease in entropy?
e.
The standard entropy for the formation of sulfur hexafluoride from the sulfur and fluorine is –348.7 J/K ⋅mol-rxn at 298.15 K. What is the standard molar entropy of sulfur hexafluoride for the reaction below? (Given: S°[S(s)] = 32.1 J/K ⋅mol and S°[F2(g)] = 202.8 J/K ⋅mol)
b.
For which of the following reactions will the entropy of a system decrease?
not b. or c.
The standard free energy change associated with the dissolution of ammonium nitrate in water is –6.73 kJ/mol at 298.15 K.
not b. or a. or e.
At what temperatures will a reaction be spontaneous if ΔrH° = +117 kJ and ΔrS° = –35 J/K?
e.
Which of the following is the equilibrium constant for the reaction below at 25 °C? (R = 8.314 J/K ⋅mol)
MgCO3(s) MgO(s) + CO2(g); ΔfG° [MgCO3(s)] = –1028.2 kJ/mol, ΔfG [MgO(s)] = –568.8 kJ/mol, and ΔfG° [CO2(g)] = –394.4 kJ/mol.
a.
Determine ΔfG° at 298 K for SnO using the data below.
Sn(s) + SnO2(s) → 2SnO(s)
Given: ΔrG° = 12.0 kJ/mol-rxn at 298K.
Substance ΔfG°(kJ/mol) at 298 K
SnO(s)
?
SnO2(s)
–515.8
a.
When a chemical process occurs under standard conditions, which of the following conditions always apply?
1. Gaseous species are at a pressure of 1 bar.
2. The solution concentration is 1 molal.
3. The temperature is 298.15 K.
d.
Which of the following statements is/are correct?
1. Spontaneous changes only occur in the direction that leads to equilibrium.
2. Exothermic reactions are always spontaneous.
3. In any chemical reaction, energy must be conserved.
d.
Which of the following compounds has the highest standard entropy per mole at 298 K?
c.
A 100 mL sample of water is placed in a coffee cup calorimeter. When 1.0 g of an ionic solid is added, the temperature decreases from 21.5 °C to 20.8 °C as the solid dissolves. For the dissolving of the solid, _____.
b.
Which of the following is true of the deposition of a gaseous substance?
d.
If ΔrG° > 0 for a reaction at all temperatures, then ΔrH° is _____ and ΔrS° is _____.
b.
Does the formation of complex molecules such as proteins and nucleic acids from more simple molecules contradict the second law of thermodynamics?
no it does not
ΔG° = 0 for a reaction indicates that _____.
b.
Which of the following linear chain alcohols is likely to have the highest standard entropy in the liquid state?
not d. or c.
What is the sign of ΔH (system) and ΔS (system) if a chemical reaction is spontaneous only at lower temperatures under standard conditions?
a
For a reaction, ΔrH° = –208.8 kJ and ΔrS° = –308.2 J/K. At what temperature will ΔrG° = 0.00 kJ?
b.
Using the given data, determine ΔrG° at 500.0 K for the reaction below.
Ba(s) + H2O(g) → BaO(s) + H2(g)
Substance
ΔfH°(kJ/mol-rxn) at 298 K
S° (J/K·mol-rxn) at 298 K
Ba(s)
0
62.8
H2O(g)
–241.8
188.7
BaO(s)
–592
70.4
H2(g)
0
130.6
b.
The standard free energy change for a chemical reaction is +13.3 kJ/mol. Which of the following is the equilibrium constant for the reaction at 125 °C? (R = 8.314 J/K⋅mol)
d.
Calculate ΔrG° for the reaction below at 425 °C,
2 HI(g) H2(g) + I2(g); K = 0.018. (R = 8.314 J/K⋅mol)
d.
The following processes occur spontaneously at 25 °C. Which of these processes is/are endothermic?
1. Ammonium nitrate, NH4NO3, dissolving in water (which is accompanied by a cooling of the water).
2. The expansion of a real gas into a vacuum (which is accompanied by a cooling of the gas).
3. Liquid water in an ice cube tray freezing into ice after being placed in a freezer.
d.
Which of the following reactions would be expected to have a positive entropy change, ΔrS° > 0?
b.
Calculate ΔS°(universe) for the combustion of acetylene at 298.15 K using the reaction below. (Given: ΔS°(system) = –194.6 J/K and ΔH°(system) = –2511.2 kJ)
not c. or b or d.
For which of the following substances is the standard free energy of formation not equal to zero at 298 K?
not c. or b. or a.
For the reaction given below, ΔH0 = −1516 kJ at 25°C and ΔS0 = −432.8 J/K at 25°C. This reaction is spontaneous _____.
SiH4(g) + 2 O2(g) → SiO2(s) + 2 H2O
a.
A flask containing helium gas is released into a closed room. Which of the following ideas concerning entropy is/are true?
e.
The standard free energy of formation of AgI(s) is –66.2 kJ/mol. ΔrG° for the reaction 2AgI(s) → 2Ag(s) + I2(s) is:
a.
The total entropy of the universe is always increasing. This is a statement of the _____ law of thermodynamics.
second
Which of the following represents the change in entropy for a system going from 142 possible microstates to 830 possible microstates? (k = 1.381 × 10-23 J/K)
d.
What is the equilibrium constant for reaction below at 25 °C? (R = 8.314 J/K⋅mol)
2 NO(g) + O2(g) 2 NO2(g); ΔfG° [NO(g)] = +86.6 kJ/mol and ΔfG° [NO2(g)] = +51.2 kJ/mol.
c.
Use the given thermodynamic data and the reaction below to calculate ΔS°(universe) for the formation of Fe2O3(s) at 298.15 K.
d.
Which of the following statements concerning entropy is/are correct?
1. The entropy of a substance increases when converted from a liquid to a solid.
2. The entropy of a substance decreases as its temperature increases.
3. All substances have positive entropy values at temperatures above 0 K
e.
Calculate ΔrG° for the reaction below at 25.0 °C.
CH4(g) + H2O(g) → 3 H2(g) + CO(g)
Given: ΔfG° [CH4(g)] = –50.8 kJ/mol, ΔfG° [H2O(g)] = –228.6 kJ/mol, ΔfG° [H2(g)] = 0.0 kJ/mol, and ΔfG° [CO(g)] = –137.2 kJ/mol.
c.
Thermodynamics can be used to determine all of the following except _____.
d.
In any chemical process, energy must be conserved. This is the _____ law of thermodynamics.
first
Calculate ΔrG° at 25.0 °C for the reaction below.
2 Na(s) + 2 H2O() → 2 NaOH(aq) + H2(g)
Given: ΔrH° = −366.6 kJ/mol-rxn and ΔrS° = −154.2 J/K⋅mol-rxn
b.
_____ changes only occur in the direction that leads toward chemical equilibrium.
spontaneous
The dissolution of ammonium nitrate occurs spontaneously in water at 25 °C. As ammonium nitrate dissolves, the temperature of the water decreases. What are the signs of ΔrH, ΔrS, and ΔrG for this process?
c.
Which of the following is the third law of thermodynamics as defined by Ludwig Boltzmann?
a.
Which of the following statements concerning entropy is not correct?
d.
If a chemical reaction is exothermic but not spontaneous, which of the following must be true?
e.
If a cube of ice at 0 °C is placed outside on a warm summer day, the ice will melt spontaneously. What are the signs of ΔrH, ΔrS, and ΔrG for the process?
d.
Which of the following is the first law of thermodynamics?
d.
What is the standard entropy change for the following reaction?
a.
Which of the following statements about entropy is true?
a.
Calculate ΔG° at 298 K for the reaction below.
I2(g) + Br2(g) → 2IBr(g)
Given: ΔrH° = –11.6 kJ/mol-rxn; ΔrS° = 12 J/K⋅mol-rxn at 298 K.
c.
At what temperatures will a reaction be spontaneous if ΔrH° = +62.4 kJ and ΔrS° = +301 J/K?
b.
For a chemical system, ΔrG° and ΔrG are equal when:
b.
At a temperature (in kelvin units) of _____, the entropy of a pure crystal is 0.0 J/K.
0 K
Which of the following statements concerning the spontaneity of chemical and physical changes is correct?
e.
A change of state occurring in a system is accompanied by 60.7 kJ of heat that is transferred to the surroundings at a constant pressure and at a constant temperature of 300 K. Calculate the ΔS(surroundings) for the process.
not d.
