For my lab (reduction of methylene blue by ascorbic acid), I have a standard plo

Question

For my lab (reduction of methylene blue by ascorbic acid), I have a standard plot that I put together, as well as Absorbance vs Time data for many trials. For one part of my lab report, it asks to write the concentrations down for H2A, HCl, and MB+ for each trial, and to find the Initial Rate (M s^-1). In the directions for this part of the report it says "You will plot absorbance vs time to determine initial rate." Where I become confused is my lecture notes for this lab say "take absorbances and convert them to concentrations and then plot this [concentration vs time graph] and find the rate by finding the initial slope of the plot."

My first question is whether I have to initially convert to concentration or not (I am leaning towards no)? My guess here is that I can find the initial rate (A s^-1) of the Absorbance vs Time slope, and then convert that rate to concentration (M s^-1) by using the extinction coefficient (Beer's Law). Would this give me the same results as converting absorbances to concentrations and then finding the slope of the Concentrations vs Time plot? If I have to convert absorbances to concentrations first, would I just divide all of the absorbances by the extinction coefficient then plot?

Next, does finding initial slope(rate) use specific values compared to finding regular slope? I know this is a lot of information to put into one question, but I am not sure what to do and google searches aren't helping out much.

Explanation / Answer

abosrbance is directly proportional to the concentration so you can directly plt a graph betweeen absorbance and time which will give you the rate of the reaction itwill be same

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