HW Ch 18: Part A

Classify each of the following processes as spontaneous or nonspontaneous.

Drag the appropriate processes to their respective bins.

Groups:

(a) Spontaneous

,

(b) Nonspontaneous

• The extraction of iron metal from iron ore

• A hot drink cooling to room temperature

• Drawing heat energy from the ocean's surface to power a ship

• The combustion of natural gas

Which process is expected to have an increase in entropy?

• Decomposition of N₂O₄ gas to NO₂ gas

• Formation of liquid water from hydrogen and oxygen gas

• Iron rusting

• Precipitation of BaSO₄ from mixing solutions of BaCl₂ and Na₂SO₄
  

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

• one
• two
• B
• A
• three

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).

• higher
• lower

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)  

• higher
• solutions have higher entropies than solid crystal
• of the difference in molar mass and complexity.
• gases have higher entropies than liquids.
• of the difference in complexity only
• of the difference in molar mass only

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)  

• of the difference in molar mass and complexity.
• of the difference in molar mass only.
• solutions have higher entropies than solid crystal
• of the difference in complexity only
• gases have higher entropies than liquids

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

Drag the appropriate items to their respective bins.

Groups:

(a) ΔSsys>0

,

(b) ΔSsys<0

• 
• 
• 
• 

Consider the bar chart showing the entropy of the system and the surroundings for the reaction A(g)→B(g)

Is the reaction spontaneous?

• No, as ΔS_univ > 0, the reaction is nonspontaneous.

• Yes, ΔS_univ > 0, and the reaction is spontaneous.

• No, as ΔS_univ < 0, the reaction is nonspontaneous.

• Yes, ΔS_univ < 0, and the reaction is spontaneous.

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.

• decrease
• overcome
• increase
• positive
• not overcome
• negative
• greater
• more
• less

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.​

• less
• decrease
• overcome
• not overcome
• negative
• greater
• increase
• positive
• more