Rate Law Equation: Solving for m & k

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SUMMARY

The discussion focuses on solving the rate law equation r = k[H+]m for the reaction involving hydrochloric acid. Participants analyze the relationship between concentration and reaction rate, utilizing logarithmic transformations to derive the values of m and k. The user successfully computes k as 0.063 and discusses the implications of plotting log(r) against log([H+]). Key insights include the importance of data fitting and understanding the reaction context for accurate analysis.

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  • Understanding of chemical kinetics and rate laws
  • Familiarity with logarithmic functions and their applications in chemistry
  • Proficiency in data analysis and graphing techniques
  • Knowledge of units and dimensional analysis in chemical equations
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Homework Statement



Concentration of Hydrochloric Acid (mol/L)

3

2

1.5

1

0.5

Reaction Rate (s/M)

1.333

13.30

38.67

73.00

1466

Homework Equations



r=k[H+]m (r is rate in M/s, k is constant, [ ] is concentration, m is order of reaction)

The Attempt at a Solution



I'm not entirely sure how to start off this problem. Using the concentration as the "x" value and the rate of reaction as the "y" value, I need to figure out m, the exponent, and if possible: k, which is the constant. How do I start?
 
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Can you think of a mathematical way of converting the r=k[H+]m equation to the y=mx+a form (where m is the exponent you are looking for, and all other things - x, y, a - are easy to calculate from the given data?
 
Borek said:
Can you think of a mathematical way of converting the r=k[H+]m equation to the y=mx+a form (where m is the exponent you are looking for, and all other things - x, y, a - are easy to calculate from the given data?

I am trying that right now. Here is where I've gotten so far:

*using line of best fit slope of the recordings (0.024s-1/M)
log(1/r)=(0.024s-1/M)[H+]+logk
*using random value in the recordings
log0.065=(0.024s-1/M)log3M+logk
-1.19854=logk
k=0.063

I'm also not sure how to get the units for k.
 
What would you expect to get if you plotted log(r) vs log(H+)?

Chet
 
To stop this being a very scholastic exercise please show the plot of your fit. We have no idea how good it is nor whether there are any systematic trends away from your line.
Also no one would be treating data of a reaction that he didn't know what it was, and what ws in the reaction mixture, so please tell us.
Does s/M mean the numbers in the second table are reciprocals of the reaction rate?
What does Log3M mean?
 
Is there any way you could manipulate the given rate to fit the rate law?
 

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