How many grams of ethanol, ch3ch2oh, should you dissolve in water to make 1.20 l of vodka (which is an aqueous solution that is 6.86 m ethanol) ?

The concentration is expressed in molarity or moles solute per liters solution. The molar mass of ethanol is 46 g/mol. To obtain a 1.2 L of vodka, the following stoichiometric calculation is done:

6.86 mol/L * 1.2 L * (46g/mol) = 378.672 g of ethanol is needed