Calcium carbide reacts with water to produce acetylene gas according to the following equation: CaC2(s) + 2H2O(l)C2H2(g) + Ca(OH)2(aq) The product gas, C2H2, is collected over water at a temperature of 25 °C and a pressure of 759 mm Hg. If the wet C2H2 gas formed occupies a volume of 8.19 L, the number of moles of CaC2 reacted was ______ mol. The vapor pressure of water is 23.8 mm Hg at 25 °C.