The Grass Doctor

Gas Stiochiometry?

Urea (H2NCONH2) is used extensively as a nitrogen source in fertilizers. 2NH3 (g) + CO2 (g) --> H2NCONH2 (s) + H2O (g) Ammonia gas at 223 C and 90. atm flows into a reactor at a rate of 500 L/min. Carbon dioxide at 223 C and 45 atm flows into the reactor at a rate of 600L/min. What mass of urea is produced per minute by this reaction assuming 100% yield?

Public Comments

1. woo ya that's fun I forget how to do this but I know it has to do with molarities
2. First you need to know the moles of the reactants. Use the ideal gas equation PV=nRT. You have the pressure, volume, (assume 1 minute) temperature. Solve for n = moles. Donn't forget to convert C into K. Use 0.082 for the R. Now that you have the moles of ammonia and CO2, you can use the chemical equation that you have. The moles of urea need to be calculated both fo rammonia and CO2 to fine the limiting reactant. Once you have that, convert the moles of urea to mass.
3. I keep answering this same question, so you must all go to the same school. Well, ignore the time per minute, as it is equal. First find mols, PV=nRT (90atm)(500L) = n(0.08206Latm/molK)(496.15K) 45000 = 40.714n 1105.27 = n ( mols NH3 ) (45atm)(600L) = n(0.08206Latm/molK)(496.15K) 27000 = 40.714n 663.16 = n ( mols CO2 ) Now, I know NH3 limits the reaction. Here's how. 1105.27mol NH3 X1mol CO2/2mol NH3 = 552.635 mol CO2 You have more CO2 than that, so NH3 drives the reaction. 1105.27 mol NH3 X 1mol Urea/2mol NH3 X 60.062g Urea/1mol Urea = 33192.36 grams Urea produced per minute.