Question

Given the absorbances and concentrations of NO2-, calculate the absorbance of a 7.0μM solution. ( Hint: Need to construct a Beer's Law Graph) Write answer to 3 decimal places. Concentration (μM) 200 100 50 25 15 10 Absorbance 1.13 0.58 0.31 0.14 0.1 0.05

Answer 1

This question can be answered easily by constructing a Beer Law Graph. I have plotted the graph that has been attached in the answer.

The regression plotter that I use, outputs a very useful piece of information. The EQUATION of the line. For this case, we are given that the eqation is best predicted by

y = 0.005638x + 0.009144.

We wanted to calculate the absorbance for solution. We simply put in the value of x and solve for y.

We get y = 0.005638*(7) + 0.009144 ==> y = 0.04861.

Hence the value of Absorbance would be 0.04861.

Note that you can plot the graph yourself using Excel. Or any other spread sheet software that you might have. It would approximately give you the same answer. (I say this because different softwares have different algorithms to compute the fit).

I hope this has helped you. Please do leave a comment in case the answer is unclear. I will be very glad to help you out.