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Ch.14 - Chemical Kinetics

Chapter 14, Problem 54b

This reaction was monitored as a function of time: AB → A + B A plot of 1/[AB] versus time yields a straight line with a slope of +0.55/Ms. b. Write the rate law for the reaction.

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Hey everyone in this example, we need to write the rate law for the reaction of X producing Y. We're told that the plot of one over X. One over our concentration of X versus time yielded the following slope. So because according to this prompt, we specifically have a plot of one over our concentration of X versus time, where X. We recognize is our reactant. This sort of plot tells us that we should have a linear rate law that would therefore be second order. So we should recall that our second order integrated rate law is one over the concentration of our reactant at a given time is equal to the rate constant times time plus one over our concentration of our reactant initially. So this is our integrated second order rate law. And we can relate this directly. Like in this example to the equation of a line where we have why? Sorry? Where we have Y representing one over our concentration of our reactant at a given time equal to M X. Which represents the place of the rate constant K. Times time. So just to be clear, K would represent m our slope where K we recall is our rate constant. And then we would have plus our Y intercept B, which represents one over our initial concentration of our reactant. So because we recognize from the equation of our line and from our integrated second order rate law, that slope is related to our rate constant K. And according to the prompt, we have a slope of positive 72 or positive 0. polarities times inverse seconds. We can say that therefore our rate law for the reaction of ex producing Y is equal to Our slope which is again given in the prompt as point positive . inverse polarity times in verse. Second since we're moving them to the numerator, which is then multiplied by our concentration of our reactant, which from the prompt is X. And because this is a second order rate law, we're going to raise this to an exponent of two. And so this would be our final answer for our second order rate law based on our equation of our line that is generated from our plot of one over concentration of reacting X versus time. So everything highlighted in yellow is our rate law expression. If you have any questions, please leave them down below. And I will see everyone in the next practice video.
Related Practice
Textbook Question

The tabulated data show the concentration of AB versus time for this reaction: AB( g)¡A( g) + B( g) Time (s) [AB] (M) 0 0.950 50 0.459 100 0.302 150 0.225 200 0.180 250 0.149 300 0.128 350 0.112 400 0.0994 450 0.0894 500 0.0812 Determine the order of the reaction and the value of the rate constant. Predict the concentration of AB at 25 s.

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Textbook Question

The reaction A¡products was monitored as a function of time. The results are shown here. Time (s) [A] (M) 0 1.000 25 0.914 50 0.829 75 0.744 100 0.659 125 0.573 150 0.488 175 0.403 200 0.318 Determine the order of the reaction and the value of the rate constant. What is the rate of reaction when [A] = 0.10 M?

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Textbook Question

This reaction was monitored as a function of time: A → B + C A plot of ln[A] versus time yields a straight line with slope -0.0045/s. a. What is the value of the rate constant (k) for this reaction at this temperature?

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Textbook Question

The decomposition of XY is second order in XY and has a rate constant of 7.02⨉10-3 M-1• s-1 at a certain temperature. a. What is the half-life for this reaction at an initial concentration of 0.100 M?

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The half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration. How long will it take for 10% of the U-238 atoms in a sample of U-238 to decay?

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Textbook Question

The half-life for the radioactive decay of U-238 is 4.5 billion years and is independent of initial concentration. If a sample of U-238 initially contained 1.5⨉1018 atoms when the universe was formed 13.8 billion years ago, how many U-238 atoms does it contain today?

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