How many mL of concentrated HCl would be required to make 200mL of a 4M solution? Specific gravity = 1.2, assay = 40%
I would first convert 40% HCl into molarity.
40% (I guess that's w/w) HCl means 40g HCl/100 g solution.
40g/36.5 = approx 1.10 mols HCl
mass = volume x density so volume = mass/density. That 100 g soln = 100/1.2 = approx 80 mL or 0.08 L; therefore, the molarity is 1.1/0.08L = about 14 M but you need to go through and redo all of these numbers more accurately.
Then use the dilution formula of
mL1 x M1 = mL2 x M2.
200 x 4 = mL2 x 14
Solve for mL2.