Question

A stock solution was diluted four times as follows: 18 ml of distilled water was added to 2 ml of stock; the resulting solution was diluted 1:3; 240 ml of distilled water was added; the resulting solution was diluted to 0.9 L. If the final concentration of the diluted solution was determined to be 100 μg/ml, the original concentration of the stock solution was...?

Answer 1

To find the original concentration of the stock solution, follow the dilution steps and use the formula (C1V1 = C2V2). In this case, the original concentration of the stock solution was 45 μg/ml.

Step-by-step explanation:

To find the original concentration of the stock solution, we need to follow the dilution steps. First, 18 ml of distilled water was added to 2 ml of stock, resulting in a solution that is diluted 1:3. Then, 240 ml of distilled water was added, and the resulting solution was diluted to 0.9 L. Finally, we can determine the original concentration using the formula (C1V1 = C2V2), where C is the concentration and V is the volume.

So, using the given information, we can calculate:

(C1)(2 ml) = (0.1)(0.9 L)

C1 = (0.1)(0.9 L) / (2 ml) = 45 μg/ml

Thus, the original concentration of the stock solution was 45 μg/ml.