Question

You are provided with a 0.1 mM solution of proflavine (MW: 209.25 g/mol), a 6 mM solution of DNA, and solid NaCl (MW: 58.44 g/mol). How many mg of NaCl would you need to make a 15 mL of the following stock solution: 1 µM proflavine, 100 mM NaCl, and 60 µM DNA?

Round your answer to one decimal digit. State only the number, not the unit.

Answer 1

Given:

Proflavine = 0.1 mM

DNA = 6 mM

Formula:

M1V1 = M2V2 -----(1)

1) Volume of proflavine required to prepare 15 ml of 1 uM solution

M1 = 0.1 mM

M2 = 1 uM = 0.001 mM

V2 = 15 ml

V1 = M2V2/M1 = 0.001 * 15/0.1 = 0.15 ml = 0.2 ml

2)

Volume of DNA required to prepare 15 ml of 60 uM solution

M1 = 6.0 mM

M2 = 60 uM = 0.06 mM

V2 = 15 ml

V1 = M2V2/M1 = 0.06 * 15/6 = 0.15 ml = 0.2 ml

3) Mass of NaCl required to make 15 ml of 100 mM solution

Molarity = moles of NaCl/volume

moles of NaCl = 100 * 15 = 1500 mmoles = 1,5 moles

Mass of NaCl = moles * molar mass = 1.5 *58.44 = 87.7 g