How can i explain hw i can prepare a 250ml of2.5M of HCl acid from;molecular weight of acid 36.5g\mole;density of acid 1.19g\ml and degree of purity of acid 37%

Answer 1

Here is the problem stated differently.
You have a solution of 37% HCl, density 1.19 g/mL. You want to use this solution to prepare 250 mL of 2.5 M HCl.

First determine the molarity of the concentrated HCl (the 37% material).
1.19 g/mL x 1000 mL x 0.37 x (1/36.5) = approximately 12 M but you should do that more accurately.
Then use c1v1 = c2v2
12M x v1 = 2.5M x 250 mL
Solve for V1. Place V1 mL of the 37% material into a 250 mL volumetric flask and add water to the mark on the flask. Mix thoroughly and copper. The resulting 250 mL will be 2.50 M HCl.