How many grams of ##NaOH## must be used to make 1 Liter of a .80 M ##NaOH## solution?

You need to relate moles of ##NaOH## to its mass. Here's how:

In ##"0.80 M "NaOH## solution, there is ##"0.80 "mol## present in ##"1000 "ml##

We can relate moles of ##NaOH## and mass of ##NaOH## by this formula:

##n=m/M## where ##n##= number of moles of ##NaOH##, ##m##= mass of ##NaOH##, and ##M##= Molar mass of ##NaOH##

Therefore,

##m##= ##M*n##

Then the number of grams of ##NaOH## used to make 1 Liter of a ##0.80 M## ##NaOH## solution is ##32g##.