CHEM 104 Lecture Notes - Lecture 9: Gas Constant, Arrhenius Equation, Elementary Reaction

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orchidpig108

23 Jul 2018

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At a higher temperature a greater fraction of reactant molecules have enough energy to surmount the activation energy barrier. A rxn is faster at a higher temperature because its rate constant is larger. A rate constant is constant only for a given reaction at a given temperature k = ae-ea/rt. A = frequency factor e = base of the natural log. R = ideal gas law constant (8. 314 j/molk) * as ea increase the reaction becomes slower * Activation energy and frequency can be obtained from experimental measurements of rate constants a function of temperature. Activation energy can be modified to be linear by taking the natural logs of both sides k = ae-ea/rt. Ln (k) = ln (a) + ln (e-ea/rt) = ln (a) + (-ea/rt) Ln (k) = ear x 1t + ln (a) * temperature and activation rate are exponentially related. * reaction rete and ea are exponentially related.

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I DO NOT GET THIS SO PLEASE EXPLAIN WHEN ANSWERING. Explain how did they figure out the slope, how did they find the y-intercep, I thought the equation is k=Ae^-Ea/RT why did they make it so that slope = -Ea/R and intercept = lnA.

This book asumes alot of these without explaining or teaching, so please help. ALSO SOLVE 14.7!!!!

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In the collision model it is assumed that reactions occur as a result of collisions between molecules with the correct kinetic energy and orientation. The minimum energy required for a reaction to occur when molecules collide is called the activation energy, E_a. The number of collisions that are favorably oriented for a reaction is described by the frequency factor, A. The Arrhenius equation relates both of these factors to the rate constant, k. k = A middot e^-E_a/(R middot T) where R = 8.314 J/(mol middot K) and T is the temperature in kelvins. Based on the activation energies and frequency factors, rank the following reactions from fastest to slowest reaction rate, assuming they are all at the same temperature. Rank from fastest to slowest reaction rate. To rank items as equivalent, overlap them. Fraction of molecules The exponential term in the Arrhenius equation is equal to the fraction of molecules, f, with kinetic energy greater than or equal to the activation energy: f = e^-E_a/(R middot T) Most scientific calculators have an e^x function as the second function of the LN button. Part B A certain reaction with an activation energy of 145 kJ/mol was run at 495 K and again at 515 K. What is the ratio of f at the higher temperature to f at the lower temperature? Express your answer numerically using one significant figure. In the collision model it is assumed that reactions occur as a result of collisions between molecules with the correct kinetic energy and orientation. The minimum energy required for a reaction to occur when molecules collide is called the activation energy, E_a. The number of collisions that are favorably oriented for a reaction is described by the frequency factor, A. The Arrhenius equation relates both of these factors to the rate constant, k: k = A middot e^-E_a/(R middot T) where R = 8.314 J/(mol middot K) and T is the temperature in kelvins. Part A Based on the activation energies and frequency factors, rank the following reactions from fastest to slowest reaction rate, assuming they are all at the same temperature. Rank from fastest to slowest reaction rate. To rank items as equivalent, overlap them. Fraction of molecules The exponential term in the Arrhenius equation is equal to the fraction of molecules, f, with kinetic energy greater than or equal to the activation energy: f = e^E_a/(R middot T) Most scientific calculators have an e^x function as the second function of the LN button. Part B A certain reaction with an activation energy of 145 kJ/mol was run at 495 K and again at 515 K. What is the ratio of f at the higher temperature to f at the lower temperature? Express your answer numerically using one significant figure. In the collision model it is assumed that reactions occur as a result of collisions between molecules with the correct kinetic energy and orientation. The minimum energy required for a reaction to occur when molecules collide is called the activation energy, Ea. The number of collisions that are favorably oriented for a reaction is described by the frequency factor, A. The Arrhenius equation relates both of these factors to the rate constant, k: k = A middot e^-E_a/(R middot T) where R = 8.314 J/(mol middot K) and T is the temperature in kelvins. Fraction of molecules The exponential term in the Arrhenius equation is equal to the fraction of molecules, f, with kinetic energy greater than or equal to the activation energy: f = e^-E_a/(R middot T) Most scientific calculators have an e^x function as the second function of the LN button. Part B A certain reaction with an activation energy of 14 kJ/mol was run at 495 K and again at 515 K. What is the ratio of f at the higher temperature to f at the lower temperature? Express your answer numerically using one significant figure.

CHEM 104 Lecture Notes - Lecture 9: Gas Constant, Arrhenius Equation, Elementary Reaction

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