15.0 mL of 8.00 M NaOH was diluted with water to 500 mL. Calculate the molarity

of the diluted NaOH solution.

My calculations:
0.015L x 8.00moles/1L x 39.997/1mole = 4.8g

M= (4.8g x 1mole/39.997) / 0.500L = 0.24M

is my workings correct? Is there another way to get to this?

1 answer

It looks ok to me but there is an easier way to do it. If you use the dilution formula you don't need to change the units; just keep everything in mL.

The dilution formula is
mL1 x M1 = mL2 x M2
15 x 8.00 = 500 x M2 and
M2 = 15*8/500 = ?

Usually I don't use the dilution formula. If I know the dilution is from 15 to 500 I know the 8.00 M will be diluted by that factor; therefore,
8.00 x (15.0/500) = ?