dilution and molarity

[emmaferry2D]

How can you tell in a question whether you are supposed to use the equation M=mol/L or M(initial)*V(initial)=M(final)*V(final)
Im getting these two concepts confused when reviewing for the final

[KatarinaReid_3H]

M=mol/L will give you the concentration. So you use this is you are given a certain amount (in grams or moles) and a certain amount of water. Then the calculation is straightforward. You will want to use MiVi=MfVf if the problem is asking you to find some new concentration based on an initial concentration, initial volume, and final volume or any 3/4 of the variables.

[Natalie Do 3F]

What helps me is writing out all the givens in the equation (am I given a volume? Am I given a molarity?) This normally well help you know which formulas to use. Also, after this step, I like to convert everything to SI units so the formulas will always work.