Answer:
30 ml of 7% solution should be added.
Step-by-step explanation:
Given:
A solution of 5% minoxidil. On hand is 60ml of a 4% solution and wishes to add some 7% solution to obtain the desired 5% solution.
Now, to get how much 7% solution should be added.
So, we put formula to express concentration as amount of volume of solution:
c = concentration, n = substance.
[tex]c=\frac{n}{v}[/tex]
Thus, the amount of substance is:
[tex]c\times v=n[/tex]
Now, in this the total amount of minoxidil is the same before and after mixing as given in question.
So, we can set the equation where V is the volume of the 7% solution:
[tex](60+V)5=(60\times 4)+7V[/tex]
⇒[tex]300+5V=240+7V[/tex]
Getting the variables one side and the numbers other side we get:
⇒[tex]300-240=7V-5V[/tex]
⇒[tex]60=2V[/tex]
Dividing both sides by 2 we get:
⇒[tex]30=V[/tex]
Volume of the solution = 30 ml
Therefore, 30 ml of 7% solution should be added.
