Thread: weight in volume calculation

How many grams of aminobenzoic acid should be used in preparing 8 fluidounces of a 5% solution in 70% alcohol? I am confused what the 5% is and 70% is referring to. So I need help figuring out the solution. Thank you.

"70% alcohol" means a solution which is 70% alcohol and 30% water. The "5%" refers to a solution that is 5% aminobenzoic acid and 95% alcohol and water.

You are correct to be confused the question should specify if this is mol% or w/vol % or w/w %. previous post is correct on 70% alcohol 30% water as solvent, 5% therefore will refer to the aminobenzoic acid, however it is not possible to tell from your question which percentage they are expecting. The simplest from your data is w/v%, w/w would require quite some calculation to work out the density of the 70% alcohol solution as this will not be the average density of the water and alcohol. however there is also sufficicent data to represent this as a mol/v% this would be unusual as when using moles to represent a concnetration one would usually use Molar (mol/dm^3)