Dilution Equation

Question

You have 40% Dextrose solution in stock and you need 1000 ml of a 2.5% solution how much stock solution is needed

Answer 1

First, find out how much Dextrose is actually needed:

0.025 x 1000 mL = 25 g (2.5% is the same as 2.5/100, or 0.025)

Second, determine the amount of the 40% stock solution:

40 g/100 mL = 25 g/x, x = 62.5 mL

So, what does this mean? You would need 62.5 mL of the stock solution and (1000 mL - 62.5 mL) of diluent to make 1000 mL of a 2.5 % solution.

Or, Q1C1 = Q2C2 (Q=quantity, C-concentration)

(1000)(2.5) = (X)(40), X = 62.5 mL