Question

How do I do 4?

g 16 Mea G vvere BBIng 6 Calculate the concentratio ou T8 Mea edu/webapps/blackboard/execute/contentUfle emdsviewßlcontent id- 2321484 1Bcourse id- 200660. I concentratio m .İd»-2321484-1&course,id-,200660 . nOW wouia you make zu mc or a 37% metnyiene oiue soiutio n wnen you nave a solution witn a starung concentration of 50%? (025 points) 3 How would you make 10 mL of a 0.25% methylene blue solution when you have a solution with a starting concentration of 75%? Convert the necessary amount amount of nL in scientific notation. (0.5 points) of methylene blue from ml to nl and write the 4. Your professor created a standard curve with a best-fit line. The equation of the line is y 0.245x+0.342. a. Calculate the concentration (in %) for the following absorbance values (1.5 points) 0.342 3.861 1.462 b. What absorbance would you expect to measure for the following concentrations (1.5 points) 18% 4% 50% Draw a graph of the best fit line. Include three errors on the graph. Explain what those errors are and then explain how you would fix those errors to make the graph more accurate. (2 points) c. 5. 6. 7. Why is it important to blank a spectrophotometer? (0.25 points) When do you blank a spectrophotometer? (0.25 points) If you were going to measure the concentration of yeast present in a nutrient broth solution, what would you put in your cuvette to blank the spectrophotometer? (Hint: Think about what portion of the dye solution you used as a blank in this week's experiment). (0.5 points)

Answer 1

2. C1V1=C2V2

50*V1=5*20

V1=2ml

Use 2ml of 50%concentrated solution to make 20ml of 5%concentrated solution

3. C1V1=C2V2

75*V1=0.25*10

V1=2.5÷75=0.034ml=3.4*10^4 nL

Use this much vol. to make 10 ml of 0.25% concentrated solution.

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