How to measure rate of reaction from Absorbance vs Time graph?

[IB`NOT`ez]

Hi,

I'm really confused as to how the rate of reaction can be measured from an absorbance vs time graph. I've thought about the following methods:

-Half life concentration

-Initial Rates method

-Beer Lambert Law to determine concentration (?)

For the first one, I can't measure half life concentration as the graph is one of absorbance vs time. I'm also not sure how to do Initial Rates method with LoggerPro as supposedly I take the slope at T roughly equaling 0.1s, however it gives me a super tiny negative value like 0.05*10 to the power of -0.05. Then I thought about using the Beer Lambert Law to determine the initial concentration based on isolating c.... but then I realized I would know the concentration since I calculated it from the start.

Google searches on Chemguide and thestudentroom doesn't help as well as they explain only absorbance vs concentration graph, can anyone please help explain?

Much appreciate any help, thanks.

[kw0573]

This is a lab question so I shouldn't explain much. I would say use Beer Lambert Law to convert your absorbance-time graph to a concentration-time graph. You can do this on LoggerPro, but if you can't figure it out, just use some spreadsheet to convert absorbance to concentration, then plot it against time to find initial rate.

[IB`NOT`ez]

1 hour ago, kw0573 said:

This is a lab question so I shouldn't explain much. I would say use Beer Lambert Law to convert your absorbance-time graph to a concentration-time graph. You can do this on LoggerPro, but if you can't figure it out, just use some spreadsheet to convert absorbance to concentration, then plot it against time to find initial rate.

Ah, thank you very much! So it is possible to convert my graph with all the data for absorbance vs time into a concentration vs time with the converted data?