Suppose you were able to measure the Relative Absorbance of each
of your dilutions with a spectrophotometer. Consider the
following data:
Concentration, M
Relative Absorbance @ xxx nm
0
0.000
0.0025
0.150
0.0050
0.295
0.0100
0.610
0.0200
1.180
Plot a standard curve using the data provided. Use Excel or
another graphing program or plot the graph by hand on graph
paper. Remember to include: title, both axes drawn with
labels & units, proper axes scales, data points, Standard Curve
line. (4 points)
You also obtained the Relative Absorbance for two solutions
with unknown concentrations. Use your standard curve to
figure out the concentration of each of these unknowns. Be
sure to show your work on your standard curve graph. Each
unknown should be clearly labeled. (2 points)
Solution
Relative Absorbance @ xxx nm
Unknown 1
0.205
Unknown 2
0.785
Keeping in mind that your dilutions were made using a regular
kitchen measuring cup, let’s consider what your data might have
looked like if you had used a 200-ml graduated cylinder
instead. Would you expect your Relative Absorbance data to
have been the same? How might your standard curve have been
affected? Explain your answers. (2 points)
What is the relationship between concentration and relative
absorbance? Provide evidence from your graph. (2
points)