Question

an order is written for 250ml of a 2% solution. you have a 6% solution in stock.
how much stock solution and how much diluent are needed to compound this order.
my answer
166.7ml diluent is added to 83.3 ml stock
is that correct?

Answer 1

No, that is not correct. Here's the correct calculation:

Let X be the amount of stock solution needed.
Then (250 - X) is the amount of diluent needed.
Using the equation: % purity of stock solution x Volume of stock solution = % purity of final solution x Total volume of final solution
We get: 6% x X = 2% x 250
Solving for X, we get: X = (2% x 250) / 6% = 83.33 ml
Therefore, the amount of diluent needed is 250 - 83.33 = 166.67 ml.

So the correct answer is: 83.33 ml of the 6% stock solution and 166.67 ml of diluent are needed to compound this order.