A pharmacist wishes to mix a solution that is 4% Minoxidil. She has on hand 60 ml of a 3% solution and wishes to add some 6% solution to obtain the desired 4% solution. How much 6% solution should she add?

1 Answer
Apr 24, 2016

Answer:

She should add 30ml.

Explanation:

We can express concentration as amount of solute/volume of solution or:

#c=n/v#

So the amount of substance #n# is given by:

#n=cxxv#

In this problem the total amount of #"Minoxidil"^("tm")# is the same before and after mixing, so we can set up this equation where #V# is the volume of the 6% solution:

#(60+V)4=(60xx3)+6V#

#:.240+4V=180+6V#

#:.6V-4V=240-180#

#:.2V=60#

#V=60/2=30"ml"#