In the following problems : First state the unknown, Second, set up the proporti

Question

In the following problems :

First state the unknown,

Second, set up the proportion equation (with the proper units)

Third, cross multiply and divide to solve for the unknown.

You must show all the steps to get full credit.

6. Suppose a particular enzyme must be added to a nutrient solution used to grow bacteria. The enzyme comes as a freeze dried powder. The manufacturer of the enzyme states that every gram of enzyme powder actually contains only 900 mg of enzyme; the rest is an inert filler that has no effect. If a recipe calls for 134.0 ounces of this enzyme for every 10.0 liters of broth and if you prepare 1000.0 liters of broth, how much of the enzyme powder will you need to add? Remember to compensate for the inert filler.

7. a. Phthalates are compounds that make plastics flexible and are used in many products including food wrap. Studies suggest that phthalates may activate receptors for estrogen, the primary female sex hormone. There is speculation that exposure to such estrogenic compounds may increase breast cancer incidence in women, reduce fertility in men, and adversely affect wildlife. One study suggested that margarine may pick up as much as 45 mg/kg of phthalates from plastic wrap. Suppose that over the course of a year, a woman consumes, on the average, 3/4 pounds of margarine per week. Suppose further that this margarine has absorbed 45 mg/kg of phthalates. How much phthalates will she be exposed to per year?

b. Suppose that the phthalates are selectively absorbed in fat tissue. Suppose that the woman described in part a) weighs 135 pounds and is 20 % fat. What will be the concentration of phthalates in her fat tissue? Express your answer in units of mg/kg.

8. A mole is an expression of amount. If the concentration of a solute in a solution is 13 mM, how many moles are there in 500 mL of this solution?

9. Suppose a particular analytical instrument can detect as little as 1 ppb benzo(a)pyrene (a carcinogen). Is the instrument sensitive enough to detect 5 molecules of benzo(a)pyrene out of 109 molecules?

10. Express each of the following as a dilution (using a /):

a. 0.1 mL of original sample + 9.9 mL of water.  

b. 5 mL sample in a total volume of 1 L.

11. You take 230 mL of suspended bacteria and grind them into a cell paste. Then, you remove 100 L of these cells and perform a test that tells you how much enzyme is present. Your test shows that 3.5 g of enzyme are present in the 100 L of cell paste.

a. What was the concentration of enzyme in the cell paste? Express your answer in units of g/L.

b. What was the concentration of enzyme in the cell paste? Express your answer in units of mg/mL.

c. How much enzyme was present in the entire original 230 mL?

12. You have 100 L of a protein sample. The sample was diluted by taking 5 L of the sample and adding 20 L of buffer. A protein assay was performed on the diluted sample. The concentration of protein in the diluted sample was 89 mg/mL. What was the concentration of protein in the original, undiluted sample? How much protein was present altogether in the original, undiluted sample

Explanation / Answer

6. Amount of enzyme in 1 gram of enzyme powder = 900 mg = 0.90 g

enzyme required to prepare 10 L of broth = 134.0 ounces

= 134.0*28.3495

= 3798.83 grams

weight of enzyme powder for 10.0 L broth = 3798.83 / 0.9

= 4220.92 grams

weight of enzyme powder for 1000.0 L broth = 4220.92*1000 / 10

= 422092 grams

= 14888.85 ounces

So, 14888.85 ounces of enzyme powder is required to prepare 1000.0L of broth.

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