Question

Compounds A and B are unstable and each decomposes by a first-order process. At 398 K, the rate constant for the decomposition of A is 3.6 X 10-5 s-1. Separate containers of A and B were prepared, with initial concentrations of 0.120 M A and 0.240 M B. After 5 hrs, it was found that the concentration of A was three times the concentration of B wwww What was the concentration of A after 5 hrs? 2) 1) What is the rate constant for the decomposition of B at 398K? 3) If the rate constant for this decomposition changes by 10% per degree Celsius what is the rate constants for the decomposition for both A and B at 450 K? 4) What would the activation energy for the decomposition of A and B? Considering that reactions typically occur through collisions 5) a) One possible explanation for the decomposition of A is that two molecules of A collide with each other and form two molecules of the product in a single elementary step. If that were the case, what reaction order would you expect? b) Another possibility is that the reaction occurs through more than one step. For example, a possible mechanism involves on step in which two molecules of A collide, resulting in the "activation" of one of them. In a second step, the activated molecule goes on to form the products. Write down this mechanism and determine which step must be rate determining in order for the kinetics of the reaction to be first order. Show explicitly how the mechanism predicts the first-order kinetics. 6) If you find a closed 2 L container that contains 0.0453 M A and 0.345 M B, what is the pressure inside the container if both A and B are gasses? Assume the decomposition products are not gasses 7) If the container is dated from 72 hours before what where the initial concentrations of A and B in the container? Assume the container was stored at 398 K the entire time

Answer 1

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