To calculate the mass of sodium chloride NaCl produced, we first need to determine the number of moles of NaCl formed when 2.5 moles of sodium Na react completely with excess chlorine gas Cl2 . Using the balanced chemical equation:2Na + Cl2 2NaClFrom the equation, we can see that 2 moles of Na react with 1 mole of Cl2 to produce 2 moles of NaCl. Since we have 2.5 moles of Na, we can calculate the moles of NaCl produced:2.5 moles Na * 2 moles NaCl / 2 moles Na = 2.5 moles NaClNow that we have the moles of NaCl, we can calculate the mass of NaCl produced. The molar mass of NaCl is approximately 58.44 g/mol 22.99 g/mol for Na + 35.45 g/mol for Cl . Mass of NaCl = moles of NaCl * molar mass of NaClMass of NaCl = 2.5 moles NaCl * 58.44 g/molMass of NaCl = 146.1 gSo, 146.1 grams of sodium chloride NaCl are produced when 2.5 moles of sodium Na react completely with excess chlorine gas Cl2 .