Question

What volume, in milliliters, of 2.0 calcium chloride stock solution would you use to make 500 ml of 0.300 m of calcium chloride cacl2 solution?

Answer 1

We can use the following formula when making diluted solutions from more concentrated solutions.
c1v1 = c2v2 
where c1 is the concentration and v1 is the volume of the concentrated solution 
and c2 is concentration and v2 is volume of the diluted solution to be prepared 

substituting these values in the equation 
2.0 M x V = 0.300 M x 500 mL 
V = 75 mL

75 mL should be taken from the stock solution and diluted upto 500 mL to make the 0.300 M solution