What volume of 6.58 M HCl is needed to make 500 mL of 3.00M HCl?

228mL of the 6.58M HCl

Explanation:

Molarity is an unit of concentration defined as the ratio between moles of solute (HCl, in this case) and liters of solution.

To make 500 mL of 3.00M HCl you need:

0.500L * (3.00mol HCl / 1L) = 1.5moles HCl

You can obtain these 1.5moles of HCl from a solution more concentrated, as 6.58M HCl. To obtain these moles you need to add:

1.5mol HCl * (1L / 6.58mol HCl) = 0.228L 6.58M HCl =

228mL of the 6.58M HCl