A chemist needs 500 mL of a 20 mM phosphate buffer.The stock solution of the buffer is 100 mM.How much stock solution should be used to make the 20 mM phosphate buffer?
A) 100 mL
B) 1000 mL
C) 10 mL
D) 1.0 mL
E) 0.1 mL

Question

Quizplus · Accepted Answer

To prepare a 20 mM phosphate buffer from a 100 mM stock solution, the chemist can use the dilution formula C1V1 = C2V2, where C1 is the concentration of the stock solution, V1 is the volume of the stock solution needed, C2 is the desired concentration, and V2 is the final volume of the solution. Plugging in the values: (100 mM)(V1) = (20 mM)(500 mL), solving for V1 gives V1 = 100 mL.

A Chemist Needs 500 ML of a 20 MM Phosphate