The Grass Doctor

chemistry problem??

Urea (H2NCONH2) is used extensively as a nitrogen source in fertilizers. It is produced commercially from the reaction of ammonia and carbon dioxide. 2 NH3(g) + CO2(g) H2NCONH2(s) + H2O(g) Ammonia gas at 223°C and 90. atm flows into a reactor at a rate of 460. L/min. Carbon dioxide at 223°C and 46 atm flows into the reactor at a rate of 600. L/min. What mass of urea is produced per minute by this reaction assuming 100% yield? ____________g/min

Public Comments

1. Consider 1 minute- PV=nRT 90 * 460 L = n * 0.08206 * 496; n=1017 moles NH3 46 * 600 L = n * 0.08206 * 496; n= 678 moles of CO2 NH3 is limiting (CO2 in excess) 678 moles of NH3 yields 678/2 moles of urea; 339 moles molar mass of urea = 60 339 moles x 60 g/mole = 20.34 kg urea per minutes 20,340 grams per minute
2. This is not that bad. Attend. First we need mols. Use the Ideal gas law. PV = nRT. NH3 first. ( both 1 minite, so equal ) (90atm)(460L) = n (0.08206Latm/molK)(496.15K) 41400 = 40.714n 1016.85 =n ( mols NH3 ) Now for CO2 (46atm)(600L) = n(0.08206)(496.15K) 27600 = 40.714n 677.90 = n (mol CO2 ) Find limiting. I suspect NH3 1016.85mol NH3 X 1mol CO2/2mol NH3 = 508.425 mol CO2 used NH3 limits and will drive reaction. 1016.85 mol NH3 X 1mol Urea/2mol NH3 X 60.062g Urea/1mol Urea = 30537.02235 grams Urea per minute. Sounds right, as this is a big industrial process.