Absorbance at 540 nm of Bromocresol Purple Dilution Series test tube concentration of sample (ug/mL) A540...

Absorbance at 540 nm of Bromocresol Purple Dilution Series

test tube	concentration of sample (ug/mL)	A540 nm	BcP dilution
1	0	0	n/a
2	0.9375	0.041	1:16
3	1.875	0.08	1:08
4	3.75	0.155	1:04
5	7.5	0.306	1:02
6	15	0.614	0:00

1. The point 0/0 is an important and valid point on this graph. Why? (Explain) Explain how a hand-drawn graph and excel graph are similar or different.

2. How is the Beer’s Law equation similar to that of a straight line? Explain each component using the letter of the component and using a set of your experimental values. BCP: 0.015M

3. Evaluate your data using the Beer’s Law equation: use the absorbance reading for the highest concentration of a solution, determine the extinction coefficient for the BCP solution you were given. Do you get the same answer if you make this calculation at another concentration?

4. Select 2 random absorbance readings on your line (that you did not actually measure) and explain two different ways you can use your graph to determine the concentration of BCP (µg/mL) of the unknown solutions that might have the selected absorbance values. ***Provide the results; what values do you determine to be the concentrations of your 2 random absorbance readings?

5. Explain why we refer to a graph such as the one you just constructed as a “standard curve” or a “calibration curve.” How would a graph such as this one be useful?

Solutions

Expert Solution

queen_honey_blossom answered 4 months ago

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