Question

How many grams of HCl are needed to produce 100g of H2O

Answer 1

well, maybe

HCl + NaOH ==> NaCl + H2O ????
If you do it that way you only need one HCl molecule for each H2O molecule because you get the second H from the NaOH.
100 g H2O is how many mols?
1+1+ 16 = 18 g/mol
100 g (1 mol / 18 g) = (100 / 18 ) mols of HCl needed
HCl = 1 + 35.5 = 36.5 g/mol
so
(100/18 )* 36.5 = 203 grams HCl