How many grams of H2O are required to react with excess CaC2 to produce 23.0 g of C2H2 according to the following equation?

Question

CaC2 + 2H2O -> Ca(OH)2 + C2H2

a.4.5
b.15.9
c.31.8
d.1.766

I think this equation works out by multiplying 2 moles by the molar mass of H2O. Please please help

Answer 1

C2H2 is 26 g/mol (2*12 + 2*1)

so
23/26 mols

twice that many mols H20 at 18 g/mol

(46/26)18 = 31.8