Question

You have a stock of streptomycin (antibiotic) with a concentration of 200 mg/mL. You add water until the concentration of streptomycin is 8 mg/mL. What dilution have you performed? (Hint: Think of how many times less concentrated your final concentration is compared to your initial. Using C1V1=C2V2) This is all the information provided in the question.

Answer 1

C₁V₁ = C₂V₂

Now, initial concentration (C₁) = 200 mg/mL

final concentration (C₂) = 8 mg/mL

V₁ are V₂ the initial and final volumes respectively;

From C₁V₁ = C₂V₂

   or V₁ / V₂ = C₂ / C₁

or V₁ / V₂ = 8 / 200 = 1 / 25

So,   V₁ : V₂ = 1 : 25

So the final solution will be 25 times less concentrated than the initial solution.