What is the volume in mL needed?

Question

What is the volume in mL needed to prepared a 0.67 M NaOH solution using 0.74 g of NaOH? The molar mass of NaOH is 40.0 g/mol. Only enter the numeric value, do not enter the unit mL. 

Answer 1

By definition 0.67 M means 0.67 moles of NaOH per liter of solution.

We can find how many moles we have in 0.74 g NaOH as follows:

0.74 g NaOH x 1 mol NaOH/40.0 g = 0.0185 moles NaOH

Now, we can find what volume that needs to go in so that it is the same as 0.67 mol/ 1 liter.

0.0185 mol / x L = 0.67 mol / 1 L

x = 0.0276 L

Converting this to mls, we have 0.0276 L x 1000 ml/L = 27.6 mls = 28 mls (2 sig. figs.)