Textbook Question
The gas-phase reaction Cl(g) + HBr(g) → HCl(g) + Br(g) 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?
Ch.14 - Chemical Kinetics
Chapter 14, Problem 57c
Indicate whether each statement is true or false. (c) Increasing the reaction temperature increases the fraction of successful collisions between reactants.
Verified step by step guidance1
Understand the concept of activation energy, which is the minimum energy that reactant molecules must possess in order to undergo a successful chemical reaction.
Recognize that at higher temperatures, the kinetic energy of the molecules increases. This means that more molecules will have energies equal to or greater than the activation energy.
Consider the Maxwell-Boltzmann distribution which shows that as temperature increases, the curve flattens and broadens, indicating that a larger fraction of molecules have higher energies.
Relate the increase in the number of molecules with sufficient energy (above the activation energy) to the likelihood of successful collisions. Successful collisions are those that result in a chemical reaction.
Conclude that increasing the reaction temperature does indeed increase the fraction of successful collisions between reactants, as more reactant molecules have the necessary energy to overcome the activation energy barrier.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Collision Theory
Collision theory states that for a reaction to occur, reactant particles must collide with sufficient energy and proper orientation. The frequency and energy of these collisions are influenced by factors such as temperature, which affects the kinetic energy of the particles.
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02:08
Collision Theory
Effect of Temperature on Reaction Rate
Increasing the temperature generally increases the kinetic energy of molecules, leading to more frequent and more energetic collisions. This results in a higher fraction of collisions that have enough energy to overcome the activation energy barrier, thus increasing the reaction rate.
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02:03Average Rate of Reaction
Activation Energy
Activation energy is the minimum energy required for a chemical reaction to occur. When temperature rises, more molecules possess energy equal to or greater than this threshold, which increases the likelihood of successful collisions and, consequently, the rate of reaction.
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02:02Activity Series Chart
Related Practice
Textbook Question
Indicate whether each statement is true or false. (a) If you measure the rate constant for a reaction at different temperatures, you can calculate the overall enthalpy change for the reaction.
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Textbook Question
Indicate whether each statement is true or false. (b) Exothermic reactions are faster than endothermic reactions.
Textbook Question
Indicate whether each statement is true or false. (c) If you double the temperature for a reaction, you cut the activation energy in half.
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