Dilution question, "70 wt. % in H2O"? If I have a solid and want to make an aqueous solution of 70%, how much water do I need? Is it as simple as weighing out 70 $\mathrm{g}$ of solid and adding water until I have 100 $\mathrm{mL}$? Will this solution be 70 wt. % $\ce{H2O}$?
To make a solution that is 70% solute by weight with $\ce{H2O}$ as the solvent, take 70 $\mathrm{g}$ of solute and add 30 $\mathrm{mL}$ of water. The resulting solution will have a mass of 100 $\mathrm{g}$, 70 $\mathrm{g}$ of which is the solute; hence, 70 wt. % in $\ce{H2O}$.