Question

How many molecules of NaOH are in 50mL of 0.1 molar concentration of NaOH?

Answer 1

Ok, first, you start with the equation:
M=#moles/volume
Rearranging the equation, you get
#moles=Mxvolume
Now simply plug-and-chug and you get
#moles=0.1x0.05=0.005moles
There is 0.005 moles of NaOH molecules, which means there are:
0.005 moles X 6.022x10^23 = 3.01x10^21 molecules of NaOH