Calculate molality of a 4.194 M H3PO4 aqueous solution whose density is 1.209 g/mL?

Question

Calculate molality of a 4.194 M H3PO4 aqueous solution whose density is 1.209 g/mL. I am having issues, do you need to use the molecular weight? Pease help !! thanks!

Answer 1

4.194 mol/L x 1 mL/1.209 g x 1 L/1000 mL x 1000=3.469 m