Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

7. Energy, Rate and Equilibrium

Gibbs Free Energy (Simplified)

GOB Chemistry

7. Energy, Rate and Equilibrium

Gibbs Free Energy (Simplified)

Previous problemNext problem

2:05 minutes

Problem 22a

Textbook Question

The following diagram portrays a reaction of the type A(s) → B(g) + C(g), where the different-colored spheres represent different molecular structures. Assume that the reaction has ∆H = +9.1 kcal/mol (+38.1 kJ/mol).

a. What is the sign of ∆S for the reaction?

Verified step by step guidance

Step 1: Analyze the reaction type. The reaction is A(s) → B(g) + C(g), where a solid (A) is breaking down into two gaseous products (B and C). This indicates a phase change from solid to gas, which typically increases disorder in the system.

Step 2: Examine the diagram. On the left side, the solid A is represented as tightly packed spheres, indicating a highly ordered structure. On the right side, the products B and C are represented as dispersed spheres, indicating a less ordered, more random distribution.

Step 3: Recall the concept of entropy (∆S). Entropy is a measure of disorder or randomness in a system. When a solid transitions to gases, the particles gain freedom of movement, leading to an increase in entropy.

Step 4: Consider the number of particles. The reaction produces two gaseous products from one solid reactant. The increase in the number of particles contributes to a higher degree of randomness and thus a positive ∆S.

Step 5: Conclude the sign of ∆S. Based on the increase in disorder and the transition from a solid to gases, the sign of ∆S for this reaction is positive.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Entropy (∆S)

Entropy, denoted as ∆S, is a measure of the disorder or randomness in a system. In chemical reactions, an increase in the number of gas molecules typically leads to an increase in entropy, as gases have more freedom of movement compared to solids. Therefore, understanding how the state of matter changes in a reaction is crucial for determining the sign of ∆S.

Phase Changes

Phase changes refer to the transitions between solid, liquid, and gas states of matter. In the given reaction, a solid (A) is converted into two gaseous products (B and C). This transition from a more ordered solid state to a less ordered gaseous state generally results in an increase in entropy, which is essential for predicting the sign of ∆S.

Thermodynamics of Reactions

Thermodynamics studies the relationships between heat, work, and energy in chemical reactions. The enthalpy change (∆H) and entropy change (∆S) are key components in determining the spontaneity of a reaction. In this case, the positive ∆H indicates that the reaction absorbs heat, but the increase in the number of gas molecules suggests that ∆S is likely positive, which can influence the overall spontaneity of the reaction.

Watch next

Master Gibbs Free Energy (Simplified) Concept 1 with a bite sized video explanation from Jules

Start learning

Related Videos

Related Practice

Textbook Question

The change of state from liquid H₂O to gaseous H₂O has ∆H = +9.72 kcal/mol(+40.7 kJ/mol) and ∆S = -26.1 cal/(mol • K) [-109 J/(mol •K)].

a. Is the change from liquid to gaseous H2O favored or unfavored by ∆H? By ∆S?

1392

views

Textbook Question

The change of state from liquid H₂O to gaseous H₂O has ∆H = +9.72 kcal/mol(+40.7 kJ/mol) and ∆S = -26.1 cal/(mol • K) [-109 J/(mol •K)].

b. What are the values of ∆H and ∆S (in kcal/mol and kJ/mol) for the change from gaseous to liquid H2O?

1432

views

Textbook Question

Two curves are shown in the following energy diagram:

b. Which curve represents the spontaneous reaction, and which the nonspontaneous?

848

views

Textbook Question

The following diagram portrays a reaction of the type A(s) → B(g) + C(g), where the different-colored spheres represent different molecular structures. Assume that the reaction has ∆H = +9.1 kcal/mol (+38.1 kJ/mol).

b. Is the reaction likely to be spontaneous at all temperatures, nonspontaneous at all temperatures, or spontaneous at some but nonspontaneous at others?

1098

views

Textbook Question

What two factors affect the spontaneity of a reaction?

1902

views

Textbook Question

What is the difference between an exothermic reaction and an exergonic reaction?

1617

views

Textbook Question

Under what conditions might a reaction be endothermic but exergonic? Explain.