# Sample Calculations II

1. Make a 50 ml agarose gel of 0.8% that is 0.5X TBE.
The TBE (Tris FW = 121.1, Borate FW = 61.8, EDTA FW = 372) stock is 10X.

2. You have a 150X stock of buffer and you need 2.5 ml of 1X. How do you make this?

3. You have a DNA solution that is 21.3 µg/µl and you want 75 µl that is 50 ng/µl. How do you make this?

4. Make 350 ml of a solution that is 25 mM Tris, 2.5 mM EDTA, and the pH is 8.0.
Tris is a base and the FW of Tris is 121.1 and EDTA is 187. Do not make a volume that exceeds 350 ml!!

5. Make two solutions of 100 ml each: A is 125 mM Na2HPO4*7H2O (FW = 268) and B is 0.25 M NaH2PO4 (FW = 120). When you mix them in this ratio (2 parts water, 1 part A, and 0.5 parts B) what will the final molarity be for each one in this mixture?

6. Make 200 ml of a 15 mM Tris, 50 mM EDTA, and 0.03 M NaCl from stock solutions that are 1M Tris, 0.5 M EDTA, and 5000 mM NaCl.

7. You are making a PCR mixture that will be 1 X of all reagents and the final volume will be 200 µl. How do you with these stocks?
300X solutionA
1500 X B
200X C
25X D

8. The protocol calls for a solution that is 1.5 % (w/v) NaCl, 2mM Tris (pH 8.0), 7% (w/v)powdered milk (you think I'm making this up?), and 0.02% (v/v) antifoam A. Is it possible to make this solution? If so, how?

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