Question

A technician needs 500.0mL of a 0.500 M MgCl2 solution for some lab procedures. The stock bottle is labeled 4.00 M MgCl2. What volume in Ml of stock solution should the technician use?

Answer 1

Answer:

Explanation:

To solve this problem, we need to obtain the number of moles of the solute we desired to prepare;

    Number of moles  = molarity x volume

Parameters given;

        volume of solution = 500mL  = 0.5L

          molarity of solution = 0.5M

   Number of moles  =  0.5 x 0.5  = 0.25moles

Now to know the volume stock to take;

           Volume of stock = $\frac{number of moles }{molarity}$

  molarity of stock  = 4M

                 volume  = $\frac{0.25}{4}$   = 0.0625L or 62.5mL