3.75 M is diluted from 350.0 to (350.0 + 125.0) so
3.75 M x 350.0/475.0 = ??M.
There is another way to do this; i.e., to rely on the definition, always a sure thing. The definition of molarity is molarity = # mols/L.
How many mols in 350.0 mL of 3.75 M HCl? That will be 0.350 x 3.75 = 1.3125 mols. Then what is the molarity when the volume is increased to 350.0 + 125.0 = 475.0 mL = 0.4750 L. That will be 1.3125 mols/0.475 L = 2.7632 which rounds to 2.76 to 3 significant figures. Just as a check, make sure this number agrees with the answer above.
Ccalculate the molarity of the resulting solution when 125.0 ml of water is added to 350.0 ml of a 3.75 M solution of HCl
1 answer