6. (6pts) You weigh one gram of protein and dissolve it in 1.0mL of water to mak

Question

6. (6pts) You weigh one gram of protein and dissolve it in 1.0mL of water to make a stock solution with a concentration of 1 g/mL. Answer the following questions in the table below 6a. Using your stock solution, you wish to make 100mL of a 10 mg/mL solution. Hint: these are your V, and C, numbers.) How do you make this working solution? What is the DF for this dilution? 6b. You also wish to make 10mL of a 0.01 mg/mL solution. How do you make this working solution? Will you use your original dilution or do you need to do this from your dilution of the original (5a)? What is the DF for this dilution? Qu.# 6 | Volume Stock | Volume of Water Dilution Factor 6a. 6b. 6h, Which solution (original stock or 6a dilution) did you use to make 6b?

Explanation / Answer

Ans. #6.a. Using       C1V1 (stock solution) = C2V2 (working solution)

Or, (1.0 g mL-1) x V1 = 10.0 mg L-1 x 100.0 mL

Or, 1000.0 mg mL-1 x V1 = 10.0 mg L-1 x 100.0 mL

            Or, V1 = (10.0 mg L-1 x 100.0 mL) / 1000.0 mg mL-1

            Hence, V1 = 1.0 mL

Therefore, required volume of stock solution = 1.0 mL

Preparation: Transfer 1.000 mL of stock solution to a 100-mL standard volumetric flask. Make the volume up to the mark with distilled water. The resultant solution is 100.0 mL of 10 mg/ mL.

# Dilution factor = Volume of stock solution / Final volume made upto

                                    = 1.0 mL / 100.0 mL

                                    = 0.01 = 10-2

#6.b. Method 1: Using stock solution:

Using C1V1 (stock solution) = C2V2 (working solution)

Or, (1.0 g mL-1) x V1 = 0.01 mg L-1 x 100.0 mL

Or, 1000.0 mg mL-1 x V1 = 0.01 mg L-1 x 100.0 mL

            Or, V1 = (0.01 mg L-1 x 100.0 mL) / 1000.0 mg mL-1

            Hence, V1 = 0.001 mL

Therefore, required volume of stock solution = 0.001 mL = 1.0 uL

# If you have good quality micropipette (say, for molecular biology work), you can transfer 1.0 uL of stock solution to a 100-mL volumetric flask and make the final volume upto the marl. It is the desired solution.

# DF = 0.001 mL / 100 mL = 10-5

# Method 2: Using #6.a. solution: If 1.0-2.0 uL micropipette is NOT available, proceed with this method.

Using C1V1 (#6a solution) = C2V2 (working solution)

Or, (10 mg mL-1) x V1 = 0.01 mg L-1 x 100.0 mL

Or, V1 = (0.01 mg L-1 x 100.0 mL) / 10.0 mg mL-1

            Hence, V1 = 0.1 mL

# Dilution factor = 0.1 mL / 100.0 mL = 10-3

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