Finding the percentage strengh

by Jamie
(Houston Tx)

If 15 grams of 1% ointment are combined with 30 grams of 2.5% ointment, what is the percentage strength of the final product ?

Reply (by Keith)

I would use the C1V1 = C2V2 formula

However, in this case it's going to be C1V1+C2V2 = C3V3

C1= Concentration of 1st Sol.

V1= Volume of 1st Sol.

C2= Concentration of 2nd Sol.

V1= Volume of 2nd Sol.

C3= Concentration of 3rd Sol.

V3= Volume of 1st Sol.


(15)(.01)+ (30)(.025)= (45)(X)


.15   +   .75   =   45X


.90   =   45X


.02   =   X


So, you'd have 45 Grams of 2%