Entropy Quiz
The question sheet
Reveal any answer as you study-
In the two-box particle model, what quantity is determined when particles redistribute so all end up in Box (b)?
- Free energy, ΔG
- Enthalpy change, ΔH
- Temperature change
- Entropy change, ΔS
Reveal answer
Answer: Entropy change, ΔS
Source evidence
PDF page 899: two boxes. Determine the entropy change, ΔS, if the particles are initially evenly distributed between the two boxes, but upon redistribution all end up in Box (b).
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According to the source, for the processes I2(s)→I2(g) and I2(s)→I2(l), what must be determined about ΔS?
- Its exact numerical value
- Whether it is positive or negative
- The activation energy
- Its units in joules
Reveal answer
Answer: Whether it is positive or negative
Source evidence
PDF page 899: temperature but somewhat higher pressure). I (s) ⟶ I (g) 2 2 I (s) ⟶ I (l) 2 2 Is ΔS positive or negative in these processes? In which of the processes will the magnitude of the entropy change be greater?
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What distinction is asked about for a chemical change involving entropy?
- ΔH versus ΔS
- ΔG versus ΔH
- ΔS versus ΔS°
- ΔS versus ΔG
Reveal answer
Answer: ΔS versus ΔS°
Source evidence
PDF page 900: 20. What is the difference between ΔS and ΔS° for a chemical change?
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In the thermite reaction Fe2O3 + 2Al → Al2O3 + 2Fe, how much heat do the surroundings absorb?
- 250 J/mol·K
- 457.18 kJ/mol
- 27.95 kJ/mol
- 851.8 kJ/mol
Reveal answer
Answer: 851.8 kJ/mol
Source evidence
PDF page 900: 24. “Thermite” reactions have been used for welding metal parts such as railway rails and in metal refining. One
PDF page 900: such thermite reaction is Fe O (s) + 2Al(s) ⟶ Al O (s) + 2Fe(s). Is the reaction spontaneous at room 2 3 2 3 temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.
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For melting 1 mole of NaCl, what quantity is calculated to determine spontaneity at 500 °C and 700 °C?
- Kp
- ΔG°
- ΔSuniv
- ΔHfusion
Reveal answer
Answer: ΔSuniv
Source evidence
PDF page 900: 27. By calculating ΔSuniv at each temperature, determine if the melting of 1 mole of NaCl(s) is spontaneous at 500
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For the reaction with ΔH°=100 kJ/mol and ΔS°=250 J/mol·K, what must be determined?
- The mass of products
- Whether spontaneous at room temp
- The equilibrium constant
- The bond energy
Reveal answer
Answer: Whether spontaneous at room temp
Source evidence
PDF page 901: 31. A reaction has ΔH° = 100 kJ/mol and ΔS° = 250 J/mol·K. Is the reaction spontaneous at room temperature?
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When using standard free energy data, each reaction is identified as spontaneous or what?
- Reversible
- Nonspontaneous
- Neutral
- Endothermic
Reveal answer
Answer: Nonspontaneous
Source evidence
PDF page 901: 33. Use the standard free energy of formation data in Appendix G to determine the free energy change for each of
PDF page 901: the following reactions, which are run under standard state conditions and 25 °C. Identify each as either spontaneous or nonspontaneous at these conditions.
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For the acetic acid dimer, held together by two hydrogen bonds, what is the total bond strength?
- 17 kJ per mole
- 30 kJ per mole
- 66.5 kJ per mole of dimer
- 250 kJ per mole
Reveal answer
Answer: 66.5 kJ per mole of dimer
Source evidence
PDF page 904: 2CH CO H(g) ⟶ (CH CO H) (g) 2 2 3 2 3 The dimer is held together by two hydrogen bonds with a total strength of 66.5 kJ per mole of dimer.
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In glycolysis, the reaction Glu + ATP → G6P + ADP has what standard free energy change?
- −30 kJ
- +8.58 kJ
- +1.7 kJ
- −17 kJ
Reveal answer
Answer: −17 kJ
Source evidence
PDF page 905: 61. In glycolysis, the reaction of glucose (Glu) to form glucose-6-phosphate (G6P) requires ATP to be present as
PDF page 905: described by the following equation: Glu + ATP ⟶ G6P + ADP ΔG° = −17 kJ In this process, ATP becomes ADP summarized by the following equation: ATP ⟶ ADP ΔG° = −30 kJ Determine the standard free energy change for the following reaction, and explain why ATP is necessary to drive this process: Glu ⟶ G6P ΔG° = ?
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For the glycolysis step ATP → ADP, what is the standard free energy change?
- +1.7 kJ
- −17 kJ
- −457 kJ
- −30 kJ
Reveal answer
Answer: −30 kJ
Source evidence
PDF page 905: described by the following equation: Glu + ATP ⟶ G6P + ADP ΔG° = −17 kJ In this process, ATP becomes ADP summarized by the following equation: ATP ⟶ ADP ΔG° = −30 kJ Determine the standard free energy change for the following reaction, and explain why ATP is necessary to drive this process: Glu ⟶ G6P ΔG° = ?
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When ammonium chloride dissolves in water spontaneously, the resulting solution feels how?
- Warm
- Boiling
- Neutral
- Cold
Reveal answer
Answer: Cold
Source evidence
PDF page 905: 64. When ammonium chloride is added to water and stirred, it dissolves spontaneously and the resulting solution
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For the decomposition of copper(I) sulfide when heated, Cu2S forms copper and what other element?
- Chlorine
- Oxygen
- Sulfur
- Hydrogen
Reveal answer
Answer: Sulfur
Source evidence
PDF page 905: 65. An important source of copper is from the copper ore, chalcocite, a form of copper(I) sulfide. When heated, the
PDF page 905: Cu2S decomposes to form copper and sulfur described by the following equation: Cu S(s) ⟶ Cu(s) + S(s) 2
Chemistry 2e
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