15. Chemical Kinetics

Energy Diagrams

14.3 Reaction Mechanisms, Catalysts, and Reaction Coordinate Diagrams | General Chemistry

Energy Diagrams, Catalysts, and Reaction Mechanisms

(c) Which step is the fastest?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/48ec39e21e3855e4-1666279987263.jpg" alt="" />

Thermodynamics and Energy Diagrams: Crash Course Organic Chemistry #15

Energy Diagrams Concept 1

Potential Energy Diagrams - Chemistry - Catalyst, Endothermic & Exothermic Reactions

Exothermic Energy Diagram: Activation Energy, Transition States and Enthalpy Change - TUTOR HOTLINE

Collision Theory

The following graph shows two different reaction pathways
for the same overall reaction at the same temperature.
Is each of the following statements true or false?
(b) For both paths, the rate of the reverse reaction
is slower than the rate of the forward reaction.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/469c020820e66709-1666279726128.jpg" alt="" />

The diagram shows the energy of a reaction as the reaction progresses.
Label each blank box in the diagram.
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/92c9fcb245838d58-1659698365923.jpg" alt="" />
a. reactants
b. products
c. activation energy (Ea)
d. enthalpy of reaction (ΔHrxn)

A key reaction in the upper atmosphere is 
O31g2 + O1g2 ¡ 2 O21g2 
For this process, the energy of activation for the forward 
reaction, Ea1fwd2, is 19 kJ/mol, and the enthalpy change for 
the reaction, ΔHrxn, is -392 kJ>mol. What is the energy of 
activation for the reverse reaction, Ea1reverse2? (LO 14.10) 
(a) 411 kJ/mol (b) 392 kJ/mol 
(c) 373 kJ/mol (d) 196 kJ/mol

Energy Diagrams Example 2

The rates of many atmospheric reactions are accelerated
by the absorption of light by one of the reactants. For example,
consider the reaction between methane and chlorine
to produce methyl chloride and hydrogen chloride:
Reaction 1: CH41g2 + Cl21g2 ¡ CH3Cl1g2 + HCl1g2
This reaction is very slow in the absence of light. However,
Cl21g2 can absorb light to form Cl atoms:
Reaction 2: Cl21g2 + hv ¡ 2 Cl1g2
Once the Cl atoms are generated, they can catalyze the
reaction of CH4 and Cl2, according to the following proposed
mechanism:
Reaction 3: CH41g2 + Cl1g2 ¡ CH31g2 + HCl1g2
Reaction 4: CH31g2 + Cl21g2 ¡ CH3Cl1g2 + Cl1g2
The enthalpy changes and activation energies for these
two reactions are tabulated as follows:
Reaction H 1kJ ,mol 2 Ea 1kJ ,mol 2
3 +4 17
4 -109 4
(b) By using the data tabulated here, sketch a
quantitative energy profile for the catalyzed reaction
represented by reactions 3 and 4.<img src="https://lightcat-files.s3.amazonaws.com/problem_images/da92311326d8dcff-1666277607896.jpg" alt="" />

The gas-phase reaction Cl1g2 + HBr1g2¡HCl1g2 + Br1g2
has an overall energy change of -66 kJ. The activation energy
for the reaction is 7 kJ. (b) What is the activation
energy for the reverse reaction?

Based on the following reaction profile, how many
intermediates are formed in the reaction A¡C?
How many transition states are there? Which step,
A¡B or B¡C, is the faster? For the reaction
A¡C, is ΔE positive, negative, or zero? [Section 14.6]
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/16746db09042a07f-1674848907214.jpg" alt="" />

Consider a reaction that occurs by the following mechanism:
A + BC SAC + B
AC + D SA + CD
The potential energy profile for this reaction is as follows:

(d) Is the reaction endothermic or exothermic? Add labels to
the diagram that show the values of the energy of reaction
ΔE and the activation energy Ea for the overall reaction.

Consider the following energy profile.

(b) How many intermediates are formed in
the reaction?

Energy Diagrams Example 1

Energy Diagrams Concept 3

The gas-phase reaction Cl1g2 + HBr1g2¡HCl1g2 + Br1g2
has an overall energy change of -66 kJ. The activation energy
for the reaction is 7 kJ. (a) Sketch the energy profile
for the reaction, and label Ea and E.

Energy Diagrams Concept 2

Consider three reactions with different values of Ea and ΔE: 
Reaction 1. Ea = 20 kJ>mol; ΔE = -60 kJ>mol 
Reaction 2. Ea = 10 kJ>mol; ΔE = -20 kJ>mol 
Reaction 3. Ea = 40 kJ>mol; ΔE = +15 kJ>mol 
(c) Which reaction is the most endothermic, and which is 
the most exothermic?

Consider this energy diagram:
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/f27c0b2460d6d312-1659701411870.jpg" alt="" />
d. Is the overall reaction endothermic or exothermic?

Representing endothermic and exothermic processes using energy diagrams | Khan Academy

Consider the following energy profile.

(c) Which step is rate limiting?

(a) Based on the following reaction profile, how many
intermediates are formed in the reaction A¡D?
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/f4110eafa7e218f1-1675083562226.jpg" alt="" />

Consider three reactions with different values of Ea and ΔE:
Reaction 1. Ea = 20 kJ>mol; ΔE = -60 kJ>mol
Reaction 2. Ea = 10 kJ>mol; ΔE = -20 kJ>mol
Reaction 3. Ea = 40 kJ>mol; ΔE = +15 kJ>mol
(b) Assuming that all three reactions are carried out at the
same temperature and that all three have the same frequency
factor A, which reaction is the fastest and which
is the slowest?

Consider a reaction that occurs by the following mechanism:
A + BC SAC + B
AC + D SA + CD
The potential energy profile for this reaction is as follows:

(b) Write structural formulas for all species present at reaction
stages 1–5. Identify each species as a reactant, product,
catalyst, intermediate, or transition state.

Consider the reaction in which HCl adds across the double
bond of ethene:
HCl + H2C“CH2¡H3C¬CH2Cl
The following mechanism, with the accompanying energy diagram,
has been suggested for this reaction:
Step 1 HCl + H2C“CH2¡H3C“CH2+ + Cl -
Step 2 H3C“CH2+ + Cl - ¡H3C¬CH2Cl
<img src="https://lightcat-files.s3.amazonaws.com/problem_images/63e3b2dd510a73ce-1659701165371.jpg" alt="" />
a. Based on the energy diagram, determine which step is rate
limiting.

The values of Ea = 248 kJ>mol and ΔE = 41 kJ>mol have 
been measured for the reaction 
H21g2 + CO21g2S H2O1g2 + CO1g2 
(b) Considering the geometry of the reactants and products, 
suggest a plausible structure for the transition state.

The decomposition of sodium bicarbonate (baking soda), 
NaHCO31s2, into Na2CO31s2, H2O1l2, and CO21g2 at constant 
pressure requires the addition of 85 kJ of heat per two moles of 
NaHCO3. (b) Draw an enthalpy diagram for the reaction.

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1. Intro to General Chemistry

2. Atoms & Elements

3. Chemical Reactions

4. BONUS: Lab Techniques and Procedures

5. BONUS: Mathematical Operations and Functions

6. Chemical Quantities & Aqueous Reactions

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9. Quantum Mechanics

10. Periodic Properties of the Elements

11. Bonding & Molecular Structure

12. Molecular Shapes & Valence Bond Theory

13. Liquids, Solids & Intermolecular Forces

14. Solutions

16. Chemical Equilibrium

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19. Chemical Thermodynamics

20. Electrochemistry

21. Nuclear Chemistry

22. Organic Chemistry

23. Chemistry of the Nonmetals

24. Transition Metals and Coordination Compounds

[BOOK CHEM] Clutch Version

Intro to Chemical Kinetics

Chemical Kinetics is the study of factors affecting reaction rates, which examines the speed by which reactants are consumed to make products.

Average Rate of Reaction

Average (General) Rate is the change in the concentration of a compound over a period of time.

Arrhenius Equation

The Arrhenius Equation&nbsp;illustrates the temperature dependence of the rate constant k.&nbsp;

Rate Law

Rate Law represents an equation for a chemical reaction that connects the reaction rate with the concentrations or pressures of the reactants and the rate constant.&nbsp;

Factors Influencing Rates

There are 4 major factors that directly influence how fast or slow a reaction proceeds.

Stoichiometric Rate Calculations

When the rate of one compound is know, the rate of another compound is calculated through rate-to-rate comparison.

According to Collision Theory:chemical reaction is successful when 2 energetic reactants successfully collide.

Integrated Rate Law

When we include the variable of time to our Rate Law then we obtain the Integrated Rate Laws.&nbsp;

Catalyst

Catalyst is a substance that increases the rate of reaction by lowering the Activation Energy (Ea) of a reaction.

Instantaneous Rate

<div title="Page 1">&nbsp;Instantaneous Rate is the rate a reaction at any particular point in time.</div>

Reaction Mechanism

<div title="Page 1">A Reaction Mechanism is a step-by-step sequence of elementary steps by which an overall chemical change occurs.</div>

Half-Life

Half-Life is the time it takes for half&nbsp;of a reactant to decay in a certain time period.

Energy Diagram represents a curved plot illustrating the energies of reactants, products and transition states of a reaction.

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