This is due at the beginning of lab 6. Read the lab protocol for this week and type your individual answers to the following questions. Each student should turn in answers at the beginning of class. You may consult other resources (textbook, library, etc.) Remember to cite information and put responses in your own words to avoid plagiarism (and loss of credit on the assignment).
1. Refer to step 2 in the protocol for lab 6. Calculate the concentration of the sample in tubes 2-5 for the serial dilutions in the chart below. You may wish to refer to http://www.wellesley.edu/Biology/Concepts/Html/standardcurve.html
Blue Solution (ml)
Total Final volume (mL)
2.5 ml from tube 1
2.5 ml from tube 2
2.5 ml from tube 3
2.5 ml from tube 4
2. If the solution in tube 1 is dark blue, do you expect the solution in tube 5 to be darker or lighter?
Lab 6 Protocol Spectrophotometry
1. To understand how spectrophotometry can be used to determine the concentration of a light-absorbing substance.
2. Learn the procedure for constructing a standard curve and practice using the standard curve to determine concentration of unknown samples.
3. Review graphing and how to determine the equation of a line.
There are many ways to measure the amount of a substance – if we have a relatively large amount, such as a spoonful of sugar, we can find its mass with a balance or find its volume by putting it in a measuring spoon. However, when we are trying to measure smaller quantities, or quantities that may be dissolved in a solution, we need to find another method for determining how much we have. For instance, it would be difficult to measure the amount of red food coloring we have in a bottle of Gatorade by weighing the bottle of Gatorade because it is mixed