text: I understand your question to mean the following: What is the mass in grams of HCl produced when 6L of molecular hydrogen measured at STP (1 atm and 273.15 K) reacts completely with excess of molecular Cl gas?\n\nPV = nRT\n\nn = PV/RT\n\nT = 273.15 K\nP = 1 atm\nR = 0.08206 L atm/mol K\nV = 6L\n\nn = (1 atm x 6L)/ (0.08206 L atm/mol K x 273.15K)\n\nn = 0.26768 mol H2\n---------------------------------------------------------------------------\nFrom the chemical equation H2(g)+Cl2(g)--->2HCl(g)\n\n(2 mol HCl/1 mol H2) 0.26768 mol H2 = 0.53536 mol HCl\n\n-----------------------------------------------------------------------------\nHydrogen Atomic weight = 1.00794\nChlorine atomic weight = 35.453\n\nThus, HCl molecular weight = 36.46094 g/mol\n--------------------------------------------------------------------------------\n\nWeight of HCL = 0.53536 mol HCl x 36.46094 g/mol = 19.52 g