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The reaction 2X + 3Y ----> Z is first order in X and second order in Y with...

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iheartbooks7891 | Student, College Freshman | (Level 1) Honors

Posted May 18, 2012 at 1:37 AM via web

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The reaction 2X + 3Y ----> Z is first order in X and second order in Y with k=0.42.

What will the rate of the reaction be if [X] = 0.15 M and [Y] = 0.633M?

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mlsiasebs | College Teacher | (Level 1) Associate Educator

Posted May 18, 2012 at 2:16 AM (Answer #1)

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The first thing we need to do is to set up the rate law equation based on the order of the reaction. The general rate law is

Rate = k[X]^m [Y]^n

Now we can substitute in the values we know

Rate = 0.42 [X]^1 [Y]^2

To find the general rate law. Now we can plug in the concentrations given and solve for the rate. 

Rate = 0.42 [0.15] [0.633]^2

And then solve for rate

Rate = 0.0252 M/s

As the concentrations change, the value of the rate will change but the general rate law will not change. The value of the rate constant, k, will be constant are the same conditions. If you change the temperature then the value of k will change but the orders of the reaction will not. 


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