Textbook Question
If a catalyst changes the activation energy of a forward reaction from 28.0 kcal/mol to 23.0 kcal/mol, what effect does it have on the reverse reaction?
2
views
Ch.7 Chemical Reactions: Energy, Rate and Equilibrium
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 7, Problem 47a
For the reaction C(s, diamond) → C(s, graphite), ∆G = -0.693 kcal/mol (-2.90 kJ/mol) at 25 °C.
a. According to this information, do diamonds spontaneously turn into graphite?
Verified step by step guidance1
Understand the role of a catalyst: A catalyst lowers the activation energy of both the forward and reverse reactions equally, without affecting the overall thermodynamic properties such as ∆G (Gibbs free energy).
Identify the activation energy change for the forward reaction: The activation energy decreases from 28.0 kcal/mol to 23.0 kcal/mol, which is a reduction of 5.0 kcal/mol.
Apply the principle of microscopic reversibility: Since the catalyst affects both the forward and reverse reactions equally, the activation energy for the reverse reaction will also decrease by the same amount, 5.0 kcal/mol.
Calculate the new activation energy for the reverse reaction: Subtract the same reduction (5.0 kcal/mol) from the original activation energy of the reverse reaction. To find the original activation energy of the reverse reaction, use the relationship between the forward and reverse activation energies and the ∆G of the reaction.
Use the relationship: Activation energy (reverse) = Activation energy (forward) + ∆G (in kcal/mol). Substitute the values to determine the original reverse activation energy, then subtract 5.0 kcal/mol to find the new activation energy for the reverse reaction.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Activation Energy
Activation energy is the minimum energy required for a chemical reaction to occur. It represents the energy barrier that reactants must overcome to transform into products. A catalyst lowers the activation energy, allowing the reaction to proceed more easily and quickly, but it does not change the overall energy difference between reactants and products.
Recommended video:
Guided course
1:06
Factors Affecting Enzyme Activity Concept 1
Gibbs Free Energy (∆G)
Gibbs Free Energy is a thermodynamic potential that measures the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure. A negative ∆G indicates that a reaction is spontaneous in the forward direction. The value of ∆G is related to the equilibrium position of the reaction and helps predict the favorability of both forward and reverse reactions.
Recommended video:
Guided course
01:04Gibbs Free Energy (Simplified) Concept 3
Catalysis and Reaction Direction
Catalysis refers to the process of increasing the rate of a reaction by adding a substance (catalyst) that is not consumed in the reaction. While a catalyst lowers the activation energy for both the forward and reverse reactions, it does not affect the Gibbs Free Energy change (∆G) of the reaction. Therefore, if the activation energy for the forward reaction decreases, the activation energy for the reverse reaction will also decrease by the same amount.
Recommended video:
Guided course
09:34The following is an endothermic reaction where Kc = 6.73 x 103.For each of the choices below predict in which direction the reaction will proceed
Related Practice
Textbook Question
What is meant by the term 'chemical equilibrium'? Must amounts of reactants and products be equal at equilibrium?
3
views
Textbook Question
Why do catalysts not alter the amounts of reactants and products present at equilibrium?
2
views
Textbook Question
The reaction between hydrogen gas and carbon to produce the gas known as ethylene is:
2 H2(g) + 2 C(s) → H2C=CH2(g), ∆G = +16.3 kcal/mol (+68 kJ/mol) 25 °C.
a. Is this reaction spontaneous at 25 °C?
Textbook Question
Why does increasing concentration generally increase the rate of a reaction?
1
views
Textbook Question
What is a catalyst, and what effect does it have on the activation energy of a reaction?
1
views