Suppose that two systems, each composed of two particles, represented by circles, have 20 JJ of total energy. Which system, A or B, has the greatest entropy? Why?

• System A has ​ (a)   energetically equivalent arrangement(s) and System B has ​ (b)   energetically equivalent arragement(s). Therefore, System ​ (c)   has the greatest entropy

For each pair of substances, identify the one that you expect to have the higher standard molar entropy (S°) at 25°C.

When comparing SO₂(g) and He(g), SO₂(g) has a ​ (a)   standard molar entropy than He(g).

When comparing KCl(aq) and KCl(s), KCl(aq) has a ​ (b)   standard molar entropy than KCl(s).

When comparing SO₃(g) and SO₂(g), SO₃(g) has a ​ (c)   standard molar entropy than SO₂(g).

When comparing H₂(g) and CH₃CH₃(g), H₂(g) has a ​ (d)   standard molar entropy than CH₃CH₃(g).
When comparing H₂S(g) and H₂Se(g), H₂S(g) has a ​ (e)   standard molar entropy than H₂Se(g).

For each pair of substances, identify the one that you expect to have the higher standard molar entropy (S°) at 25°C.

When comparing HCOOH(g) and HCOOH(l), HCOOH(g) has a ​ (a)   standard molar entropy than HCOOH(l).

Complete the sentences to explain the reasons for your choices.

KCl(aq) has a higher standard molar entropy than KCl(s) mainly because ​ (b)   .

H₂(g) has a lower standard molar entropy than CH₃CH₃(g) mainly because ​ (c)  

He(g) has a lower standard molar entropy than SO₂(g) mainly because ​ (d)  

HCOOH(l) has a lower standard molar entropy than HCOOH(g) mainly because ​ (e)  

Complete the sentences to explain the reasons for your choices.

SO₂(g) has a lower standard molar entropy than SO₃(g) mainly because​ (a)  

H₂S(g) has a lower standard molar entropy than H₂Se(g) mainly because ​ (b)  

Without doing any calculations, determine the sign of ΔSsysΔSsys for each of the following chemical reactions.

Drag the appropriate items to their respective bins.

Does raising the temperature make the reaction more spontaneous or less spontaneous?

• At the given temperature, the ​ (a)   in the change in entropy of the system (ΔS_sys) is ​ (b)   by the large​ (c)   in the cha​nge in entropy of the surroundings (ΔS_surr), resulting in a ​ (d)   ΔS_univ and a spontaneous process.

Does raising the temperature make the reaction more spontaneous or less spontaneous?

• At higher temperatures, ΔS_surr is ​ (a)   than it is at lower temperatures, which means an increase in temperature corresponds to a(n) ​ (b)   in ΔS_univ.

• Thus, raising the temperature makes the reaction ​ (c)   spontaneous.​

Part 1:

Consider the combustion of propane gas:

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g), ΔH_rxn = −2044 kJ

Calculate the entropy change in the surroundings when this reaction occurs at 25°C

Express your answer in joules per kelvin to three significant figures.

ΔS_surr = (a)   J/K

Given the values of ΔH°_rxn, ΔS°_rxn , and T, determine ΔS_univ.

ΔH°_rxn = 127 kJ, ΔS°_rxn = −262 J/K, T = 293 K

Express your answer in joules per kelvin to three significant figures.

ΔS_{univ = (a)}   J/K

Given the values of ΔH°_rxn, ΔS°_rxn, and T, determine ΔS_univ

ΔHº_rxn = −127kJ, ΔS°_rxn = −262 J/K, T = 293K

Express your answer in joules per kelvin to three significant figures.

ΔS_univ = (a)   J/K

Given the values of ΔH°_rxn, ΔS°_rxn, and T, determine ΔS_univ.

ΔH°_rxn = −127 kJ, ΔS°_rxn = −262 J/K, T = 775 K

Express your answer in joules per kelvin to two significant figures.

ΔS_univ = (a)   J/K

Given the values of ΔH°_rxn, ΔS°_rxn, and T, determine ΔS_univ.

ΔH°_rxn = −127 kJ, ΔS°_rxn = 262 J/K, T = 293 K

Express your answer in joules per kelvin to three significant figures.

ΔS_univ = (a)   J/K

Predict whether or not each reaction is spontaneous. (Assume that all reactants and products are in their standard states.)

Drag the appropriate items to their respective bins.

Part 1:

Fill in the blanks in the table below where both ΔH and ΔS refer to the system.

Drag the appropriate labels to their respective targets.

1: ​ (a)  

2:​ (b)  

3: ​ (c)  

4: ​ (d)  

5:​ (e)  

Part 2:

Fill in the blanks in the table below where both ΔH and ΔS refer to the system.

Drag the appropriate labels to their respective targets.

6:​ (a)  

7:​ (b)  

1. 1. C2H2 (g) + H2 (g) → C2H4 (g)

Express your answer in joules per kelvin to one decimal place.

ΔS°_rxn = (a)   ._ J/K

2. 2. C (s,diamond) + H2O (g) → CO (g) + H2 (g)

   Express your answer in joules per kelvin to one decimal place.

3. ΔS°_rxn = (a)   ._ J/K

3. 3. CO (g) + H2O (g) → H2 (g) + CO2 (g)

   Express your answer in joules per kelvin to one decimal place.

   ΔS°_rxn = (a)   ._ J/K

4. 4. 2H2S (g) + 3O2 (g) → 2SO2 (g) + 2H2O (l)

   Express your answer in joules per kelvin to one decimal place.

5. ΔS°_rxn = (a)   ._ J/K

Try to rationalize the sign of ΔS°_rxn in each case.

• Part A: (C2H2 (g) + H2 (g) → C2H4 (g))

• The answer is negative, which is consistent with the fact that the number of moles of ​ (a)   is ​ (b)   .

  Part B: (C (s,diamond) + H2O (g) → CO (g) + H2 (g))
  The answer is positive, which is consistent with the fact that the number of moles of ​ (c)   is ​ (d)   .

Try to rationalize the sign of ΔS°_rxn in each case.

• Part C: (CO (g) + H2O (g) → H2 (g) + CO2 (g))
  The change is small because the number of moles of ​ (a)   is ​ (b)   .

• Part D: (2H2S (g) + 3O2 (g) → 2SO2 (g) + 2H2O (l))
  The answer is negative, which is consistent with the fact that the number of moles of ​ (c)   is ​ (d)   .