Question

To 225 mL of a 0.80 M solution of KI, a student adds enough water to take 0.5 L of a more dilute KI solution. What is the molarity of the new solution?

Answer 1

This is a dilution, for that we use: \(M_1V_1=M_2V_2\)

where M is molarity and V is volume.

so initially you have 225 mL of 0.8 M KI, then you add water and end up with 0.5 L.

\(225~mL*0.8~M=M_2*500~ mL\) (make sure use the same units on both sides)

\(M_2=\dfrac{225~mL*0.8~M}{500~mL}\)