# Making a solution with two solutes

I need to make a solution that has a 15% (wt/wt%) HCl acid concentration and a 6% (wt/wt%) NaI concentration. I'm not sure yet how much of this solution I will be required to make so a general recipie would be awesome. I would also like to know how to make the concentrations wt/vol% as well.

• Are you sure it is vol/vol% for HCl and NaI? There are two problems with defining composition in this way. The first is that volumes are not additive, especially over such a large range of concentrations (100% to 15%). The second is that NaI is not a liquid at 100% concentration - it's an ionic solid, and HCl is a gas at room temperature. Typically concentrations made from combining aqueous solutions are specified in either molarity, molality, wt/wt%, or wt/vol%. You can use vol/vol% for mixtures of pure substances if you ignore $\Delta V$ of mixing. Jun 26 '14 at 1:18