Calculating IPA per Solution

[Mcortese]

Hi, 

I would like to know how to calculate 80% IPA into 2,000 ml bottle. How much of it in grams/oz to add? 

[Alexmadonik]

As I tell my students almost every day, you CAN'T calculate it.  You have to look it up, because you don't know the volume of mixing that is determined by the INTERACTION between isopropanol and water.  I found some data in 

Densities and Refractive Indices of Alcohol-Water Solutions of n-Propyl, Isopropyl, and Methyl Alcohols.

• Kwang-Yu Chu and A. R. Thompson

Cite this: J. Chem. Eng. Data 1962, 7, 3, 358–360

Densities and Refractive Indices of Alcohol-Water Solutions n-Propyl, Isopropyl, and Methyl Alcohols

You'll have to interpolate between 77.9% and 89.8% to find the correct density of 80% aqueous isopropanol.

Here's another source (The Engineers' Toolbox):

Density of aqueous solutions of organic substances as sugars and alcohols 

It states that the density of 80% isopropanol is 0.9696 g/mL at 20°C.

In molality terms, 66.556 mole ispropanol per kg or water.

Alex Madonik

Peralta Community College

Oakland, CA