Question 1

Which relationship or statement best describes ΔS° for the following reaction? KCl(s) → K⁺(aq) + Cl⁻(aq)

Accepted Answer

The reaction involves a solid reacting with two aqueous ions, leading to an increase in disorder or randomness. Therefore, ΔS° is expected to be positive.

Question 2

In which one of these pairs will the entropy of the first substance be greater than that of the second? Assume P and T are the same for each pair, unless stated otherwise.

Accepted Answer

The answer of In which one of these pairs will...

Question 3

Which relationship or statement best describes ΔS° for the following reaction? 2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

Accepted Answer

The reaction involves the formation of 3 gaseous products (6HF, N₂, Cl₂) from 4 gaseous reactants (2NH₃, 2ClF₃). This means that there is an increase in the number of moles of gas particles, which results in an increase in disorder or entropy. Therefore, ΔS° is expected to be greater than 0.

Question 4

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Accepted Answer

The answer of Which of the following pairs has the...

Question 5

Which one of the following phase changes decreases the entropy of the system?

Accepted Answer

Condensation leads to a decrease in entropy because the gas becomes more ordered as it transforms into a liquid. The particles in a gas have more freedom of movement compared to those in a liquid, so when a gas condenses, the particles become more confined and ordered, and the entropy decreases.

Question 6

Which relationship or statement best describes ΔS° for the following reaction? O₃(g) + NO(g) → O₂(g) + NO₂(g)

Accepted Answer

The number of gas molecules is the same on both sides of the reaction (2 reactant molecules and 2 product molecules), suggesting that the entropy change (ΔS°) is approximately zero.

Question 7

You are given pure samples of ammonia, NH₃(g), and nitrogen trifluoride, NF₃(g). What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

Nitrogen trifluoride has a more complex molecular structure than ammonia, meaning that it has more ways in which its molecules can move and vibrate. This greater complexity and number of possible configurations result in a higher standard molar entropy for NF₃(g) compared to NH3(g) at 298 K. Therefore, the standard molar entropy of nitrogen trifluoride is larger than that of ammonia, so the correct option is B.

Question 8

Which relationship best describes ΔS° for the following reaction? 8H₂(g) + S₈(s) → 8H₂S(g)

Accepted Answer

The reaction involves the formation of a gas from a solid and a gas. The increase in the degree of freedom due to the formation of gas molecules leads to an increase in entropy, so ΔS° is positive.

Question 9

Which, if any, of the following processes is spontaneous under the specified conditions?

Accepted Answer

The answer of Which, if any, of the following processes...

Question 10

You are given pure samples of ethane, C₂H₆(g), and toluene, C₇H₈(l). What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

The answer of You are given pure samples of ethane,...

Question 11

When a sky diver free-falls through the air, the process is

Accepted Answer

The process of free-falling through air is spontaneous because it occurs naturally without the need for any external stimulation or intervention. The force of gravity acting on the skydiver causes him to accelerate towards the ground, and this process occurs spontaneously without any external force needed. Choice A is incorrect because the skydiver is actually accelerating due to the force applied by gravity, which is a spontaneous process. Choice B is incorrect because the skydiver is losing potential energy, but this is also a spontaneous process. Choice C is irrelevant to whether the process is spontaneous or not. Choice E is also incorrect because the skydiver is not in equilibrium during free-fall.

Question 12

Which relationship or statement best describes ΔS° for the following reaction? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

Accepted Answer

The reaction involves 5 moles of gas reacting to produce 4 moles of gas, indicating a decrease in the number of gas molecules and thus a decrease in entropy (ΔS° < 0).

Question 13

Which relationship or statement best describes ΔS° for the following reaction? C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

Accepted Answer

The reaction involves a decrease in the number of gas molecules from 3 to 2, which typically leads to a decrease in entropy (ΔS° < 0).

Question 14

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl₂(g) → PbCl₂(s)

Accepted Answer

When a solid reacts with a gas to form a solid, the entropy decreases because gas molecules are more disordered than solid molecules. Therefore, ΔS° for this reaction is negative.

Question 15

You are given pure samples of pentane, CH₃CH₂CH₂CH₂CH₃(l), and 1,3-pentadiene, CH₂=CHCH=CHCH₃(l). What prediction would you make concerning their standard molar entropies at 298 K?

Accepted Answer

Pentane, being a saturated hydrocarbon, has more freedom of rotation around its single bonds compared to 1,3-pentadiene, which contains double bonds restricting rotation. This increased freedom of movement in pentane leads to a higher standard molar entropy at 298 K.

Question 16

Which relationship best describes ΔS° for the following reaction? CO(g) + H₂O(g) → CO₂(g) + H₂(g)

Accepted Answer

The answer of Which relationship best describes ΔS° for the...

Question 17

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O₂(g) → Hg(l) + SO₂(g)

Accepted Answer

The reaction involves a solid and two gases as reactants, and a liquid and a gas as products. The state of matter is changing from solid and gas to liquid and gas, increasing the disorder or entropy of the system, making ΔS° > 0.

Question 18

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO₂(g) → CaCO₃(s)

Accepted Answer

The reaction involves the conversion of one solid and one gas into a single solid product, which decreases the disorder in the system, indicating that ΔS° < 0.

Question 19

Which relationship or statement best describes ΔS° for the following reaction? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

Accepted Answer

The reaction involves the formation of a solid from aqueous reactants, which decreases the disorder of the system, leading to ΔS° < 0.

Question 20

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Accepted Answer

The answer of In which one of the following pairs...

Quiz 20: Thermodynamics: Entropy, Free Energy, and Reaction Direction

Which relationship or statement best describes ΔS° for the following reaction? KCl(s) → K⁺(aq) + Cl⁻(aq)

In which one of these pairs will the entropy of the first substance be greater than that of the second? Assume P and T are the same for each pair, unless stated otherwise.

Which relationship or statement best describes ΔS° for the following reaction? 2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Which one of the following phase changes decreases the entropy of the system?

Which relationship or statement best describes ΔS° for the following reaction? O₃(g) + NO(g) → O₂(g) + NO₂(g)

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? 8H₂(g) + S₈(s) → 8H₂S(g)

Which, if any, of the following processes is spontaneous under the specified conditions?

You are given pure samples of ethane, C₂H₆(g) , and toluene, C₇H₈(l) . What prediction would you make concerning their standard molar entropies at 298 K?

When a sky diver free-falls through the air, the process is

Which relationship or statement best describes ΔS° for the following reaction? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl₂(g) → PbCl₂(s)

You are given pure samples of pentane, CH₃CH₂CH₂CH₂CH₃(l) , and 1,3-pentadiene, CH₂=CHCH=CHCH₃(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? CO(g) + H₂O(g) → CO₂(g) + H₂(g)

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O₂(g) → Hg(l) + SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO₂(g) → CaCO₃(s)

Which relationship or statement best describes ΔS° for the following reaction? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Quiz 20: Thermodynamics: Entropy, Free Energy, and Reaction Direction

Which relationship or statement best describes ΔS° for the following reaction? KCl(s) → K+(aq) + Cl−(aq)

In which one of these pairs will the entropy of the first substance be greater than that of the second? Assume P and T are the same for each pair, unless stated otherwise.

Which relationship or statement best describes ΔS° for the following reaction? 2NH3(g) + 2ClF3(g) → 6HF(g) + N2(g) + Cl2(g)

Which of the following pairs has the member with the greater molar entropy listed first? All systems are at 25°C.

Which one of the following phase changes decreases the entropy of the system?

Which relationship or statement best describes ΔS° for the following reaction? O3(g) + NO(g) → O2(g) + NO2(g)

You are given pure samples of ammonia, NH3(g) , and nitrogen trifluoride, NF3(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? 8H2(g) + S8(s) → 8H2S(g)

Which, if any, of the following processes is spontaneous under the specified conditions?

You are given pure samples of ethane, C2H6(g) , and toluene, C7H8(l) . What prediction would you make concerning their standard molar entropies at 298 K?

When a sky diver free-falls through the air, the process is

Which relationship or statement best describes ΔS° for the following reaction? 2H2S(g) + 3O2(g) → 2H2O(g) + 2SO2(g)

Which relationship or statement best describes ΔS° for the following reaction? C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l)

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl2(g) → PbCl2(s)

You are given pure samples of pentane, CH3CH2CH2CH2CH3(l) , and 1,3-pentadiene, CH2=CHCH=CHCH3(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? CO(g) + H2O(g) → CO2(g) + H2(g)

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O2(g) → Hg(l) + SO2(g)

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO2(g) → CaCO3(s)

Which relationship or statement best describes ΔS° for the following reaction? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq)

In which one of the following pairs will the first system have a higher entropy than the second? Assume P and T are the same for each pair, unless stated otherwise.

Which relationship or statement best describes ΔS° for the following reaction? KCl(s) → K⁺(aq) + Cl⁻(aq)

Which relationship or statement best describes ΔS° for the following reaction? 2NH₃(g) + 2ClF₃(g) → 6HF(g) + N₂(g) + Cl₂(g)

Which relationship or statement best describes ΔS° for the following reaction? O₃(g) + NO(g) → O₂(g) + NO₂(g)

You are given pure samples of ammonia, NH₃(g) , and nitrogen trifluoride, NF₃(g) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? 8H₂(g) + S₈(s) → 8H₂S(g)

You are given pure samples of ethane, C₂H₆(g) , and toluene, C₇H₈(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship or statement best describes ΔS° for the following reaction? 2H₂S(g) + 3O₂(g) → 2H₂O(g) + 2SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)

Which relationship or statement best describes ΔS° for the following reaction? Pb(s) + Cl₂(g) → PbCl₂(s)

You are given pure samples of pentane, CH₃CH₂CH₂CH₂CH₃(l) , and 1,3-pentadiene, CH₂=CHCH=CHCH₃(l) . What prediction would you make concerning their standard molar entropies at 298 K?

Which relationship best describes ΔS° for the following reaction? CO(g) + H₂O(g) → CO₂(g) + H₂(g)

Which relationship or statement best describes ΔS° for the following reaction? HgS(s) + O₂(g) → Hg(l) + SO₂(g)

Which relationship or statement best describes ΔS° for the following reaction? CaO(s) + CO₂(g) → CaCO₃(s)

Which relationship or statement best describes ΔS° for the following reaction? BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)