Question

A pharmacist wishes to mix a solution that is 7% Minoxidil. She has on hand 60 ml of a 2% solution and wishes to add some 9% solution to obtain the desired 7% solution. How much 9% solution should she add?

Answer 1

The pharmacist needs to add 150 mL of the 9% Minoxidil solution to 60 mL of the 2% solution to make a 7% solution.

Step-by-step explanation:

A pharmacist wants to mix a solution that is 7% Minoxidil. She has 60 mL of a 2% solution and wants to add a 9% solution to reach the desired concentration. To solve this problem, you can use the equation for dilutions which is C1V1 = C2V2, where C1 and C2 are the concentrations of the solutions before and after dilution, and V1 and V2 are the volumes before and after dilution, respectively.

Let's let x be the volume of the 9% solution to be added. So, the total final volume V2 will be (60 + x) mL. The equation reflecting the desired concentration will be:

(2%)(60 mL) + (9%)x = (7%)(60 mL + x).

Solving for x will give us the volume of 9% solution needed:

1.2 mL + 0.09x = 4.2 mL + 0.07x,

0.09x - 0.07x = 4.2 mL - 1.2 mL,

0.02x = 3 mL,

x = 3 mL / 0.02,

x = 150 mL.

So, the pharmacist needs to add 150 mL of the 9% solution to achieve the desired 7% solution.