Pozzi Lab -Wet Lab Training Questions 1, DNA extractions and/or cleanup uses 70%

Question

Pozzi Lab -Wet Lab Training Questions 1, DNA extractions and/or cleanup uses 70% ethanol (EtOH). How would you prepare 50 mL of 70% EtOH (Le, what volumes of 100% EtOH and H20 would you combin som35mL of EtON So-3smL 15mL of Ha tot of soln 100 2. 50X TAE buffer contains the following, which are dissolved then brought up to 1L with qH,0: 242 g Tris [MW 121.14 g/mole) 100 mL 0.5 M EDTA [MW 372.24 g/mole] 57.1 mL glacial acetic acid [99.8%, 17.4 M, Mw = 60.05 g/mole] Calculate the molarity of each component in the final 50X TAE buffer stock. 3. How would you make 1 L of 1X TAE buffer with the 50X TAE buffer stock (i.e. what volumes of 50X TAE buffer and qH20 would you combine)? 4. Using the MW given in Question 2, calculate the amount of EDTA required to make 2 L of 0.5M EDTA.

Explanation / Answer

Ans 2

Total volume of solution V = 1 L H2O + 0.1 L EDTA + 0.0571 L acetic acid

= 1.1571 L

Molarity of Tris = moles/V

= mass/V x MW

= 242/(1.1571*121.14) = 1.726 M

Moles of EDTA = 0.5 x 0.100 = 0.05 moles

Molarity of EDTA = 0.05/1.1571 = 0.0432 M

Moles of acetic acid = 17.4 x 0.998 x 0.0571 = 0.9915 moles

Molarity of acetic acid = 0.9915/1.1571 = 0.8569 M

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