Plotting the data using Beer-Lambert law For the spectroscopy lab we had a stock dye ($\pu{1.00E-4 M}$ Erioglaucine Blue) that we had to dilute. We had to dilute $\pu{1 mL},$ $\pu{3 mL},$ $\pu{5 mL},$ $\pu{8 mL},$ and $\pu{10 mL}$ in $\pu{100 mL}$ of water and measure their absorbance $A.$ I obtained the following data:
$$
\begin{array}{ccc}
\hline
V/\pu{mL} &amp; A &amp; λ/\pu{nm} \\
\hline
1 &amp; 0.127 &amp; 629.0 \\
3 &amp; 0.342 &amp; 626.2 \\
5 &amp; 0.550 &amp; 627.6 \\
8 &amp; 0.850 &amp; 628.3 \\
10 &amp; 1.064 &amp; 626.9 \\
\hline
\end{array}$$
How do I get the concentration in $\pu{mol L^-1}$ in order to make the graph? If I could get one example from this data set I should be able to calculate the rest for myself. I just need a head start.
You need to be aware of the dilution formula in order to plot concentration on the x-axis and absorbance on the y-axis:
$C_iV_i = C_fV_f$
So your initial concentration is your stock concentration and your initial volume is listed in the table. Your final volume is $\pu{100 mL}$. Can you determine $C_f$? With that you would be able to calculate all 5 different concentrations.
Keep in mind, that you need to fix the wavelength of measurement. Since the spectrum is very broad, $\pu{1 nm}$ will not make a huge difference. You may not have perfect linearity.