An assay requires a 70 % (v/v) solution of EtOH but your lab only has a 99.3 % (v/v) stock solution of EtOH. How much of the stock solution will you need to make 3.0 L of the assay EtOH solution?

Question

An assay requires a 70 % (v/v) solution of EtOH but your lab only has a 99.3 % (v/v) stock solution of EtOH. How much of the stock solution will you need to make 3.0 L of the assay EtOH solution?

Answer 1

To solve this question, we can use the equation for dilution: C1V1 = C2V2

C1= assay concentration (given) => 0.7

V1 = assay solution (given) => 3 L

C2 = stock concentration (given) => 0.993

V2 = stock volume (what we need to solve for) => ?

Plugging into the equation above gives us the following: (0.7)(3 L) = (.993)* V2 => V2= stock volume = 2.1 L

Answer: 2.1 L