Nitrogen trichloride, an unstable liquid, is placed in a 3.00 L container at 29ºC. The initial pressure in the flask is 1.00 atm due to the presence of air. On exposure to light the NCl3 decomposes completely as follows: 2 NCl3(l) ? N2(g) + 3 Cl2(g) . The final total pressure in the flask is 1.88 atm. What mass of NCl3 was originally present in the flask?