how many mL of concentrated (15 M) hydrochloric acid (HCL) are required to prepare 500 mL of 6 M hydrochloric acid?

To determine how many milliliters (mL) of concentrated hydrochloric acid (HCl) are needed to prepare 500 mL of 6 M hydrochloric acid, we can use the equation:

M1 * V1 = M2 * V2

Where:
M1 = initial concentration of HCl
V1 = volume of concentrated HCl
M2 = final concentration of HCl
V2 = final volume of HCl solution

In this case:
M1 = 15 M (concentration of concentrated HCl)
V1 = unknown (volume of concentrated HCl we want to find)
M2 = 6 M (desired final concentration)
V2 = 500 mL (final volume of HCl solution)

Plugging in these values into the equation, we get:

15 M * V1 = 6 M * 500 mL

Simplifying the equation, we have:

V1 = (6 M * 500 mL) / 15 M

V1 = (6 * 500) / 15

V1 = 200 mL

Therefore, you would need 200 mL of concentrated hydrochloric acid (HCl) to prepare 500 mL of 6 M hydrochloric acid solution.