Chemistry help
posted by Julie .
I am confused as to how to solve the below problem. I am not sure which formula to use. At first I thought I calculate the molar mass of NaOH, followed by calculating moles of NaOH. But I don't have the mass of NaOH to calculate moles. Do I convert 10mL to grams to Be able to calculate moles and then the molarity? OR do I use Ci x Vi = Cf x Vf, to solve for the molarity?
If 2.0 ml of 0.010 M of NaOH is mixed with enough water to make the total volume 8mL, what is molarity of the resulting solution?

There are numerous ways to do this but the shortest way is to use the dilution formula that you have in the last sentence of your post.
I even take a short cut with that.
0.01M NaOH x (2.0 mL/8 mL) = ? M.
Note: It isn't needed, but you really do have the mass.
moles NaOH = M x L = ?
Then mols NaOH = grams NaOH/molar mass NaOH.
Knowing mols NaOH and molar mass you can calculate grams.