Can I Use Rates Instead of Rate Constants in an Arrhenius Plot?

In summary, the person is struggling with finding the shelf life using the Arrhenius equation in chemistry. They have converted percentages into rates and have two data points at different temperatures. They know they can find the activation energy and A constant by plotting 1/T vs. lnk, but they do not have the k value. They can solve this by using simultaneous equations.
  • #1
mycotheology
89
0
Heres the question:
http://img215.imageshack.us/img215/1185/screenshot5xq.png [Broken]
Kinetics is probably my weakest area in chemistry so I'm struggling. To find the shelf life, I need to use the Arrhenius equation but I don't know the activation energy Ea or the A constant. So I converted 2 those percentages into rates and got:
At 40C, rate = 0.082 %/month
At 60C, rate = 0.39 %/month

I know that if I plot 1/T vs. lnk, I get an Arrhenius plot and then I can find Ea from the slope and A from the y-intercept but I don't have k. Can I just use the rates that I have instead of k?
 
Last edited by a moderator:
Chemistry news on Phys.org
  • #2
You have two data points and two unknowns, that means you should be able to find both solving system of two equations.
 
  • #3
Can you elaborate on that a bit. Do you mean use simultaenous equations?
 
  • #4
Yes.
 
  • #5


Yes, you can use the rates instead of the specific rate constant k in the Arrhenius equation. The rate of a reaction is equal to the rate constant multiplied by the concentrations of the reactants, so you can use the rates you have calculated in place of k. Just be sure to use the same units for the rates and temperature in the Arrhenius plot.
 

1. What is an Arrhenius plot?

An Arrhenius plot is a graphical representation of the relationship between the rate of a chemical reaction and the temperature at which it occurs. It is named after Swedish chemist Svante Arrhenius who developed the concept of activation energy.

2. How is an Arrhenius plot used in scientific research?

An Arrhenius plot is commonly used to determine the activation energy of a chemical reaction, which is a measure of the minimum energy required for a reaction to occur. It can also be used to study the effect of temperature on reaction rates and to compare the kinetics of different reactions.

3. What is the mathematical equation used to create an Arrhenius plot?

The equation used to create an Arrhenius plot is the Arrhenius equation, which is k = A * e^(-Ea/RT), where k is the rate constant, A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, and T is the absolute temperature.

4. What are the key features of an Arrhenius plot?

The key features of an Arrhenius plot include a linear relationship between the natural logarithm of the rate constant and the inverse of the temperature, a negative slope that represents the activation energy, and a y-intercept that represents the natural logarithm of the pre-exponential factor.

5. Are there any limitations to using an Arrhenius plot?

While an Arrhenius plot is a useful tool for studying the kinetics of a reaction, it does have some limitations. It assumes that the reaction follows the Arrhenius equation, which may not always be the case. Additionally, experimental errors and uncertainties in temperature measurements can affect the accuracy of the results.

Similar threads

Replies
3
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
1K
Replies
2
Views
3K
Replies
1
Views
1K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
2K
  • Biology and Chemistry Homework Help
Replies
9
Views
7K
  • Introductory Physics Homework Help
Replies
1
Views
9K
  • Biology and Chemistry Homework Help
Replies
5
Views
3K
Back
Top