Urea is synthesized industrially by the reaction of ammonia with carbon dioxide

Question

Urea is synthesized industrially by the reaction of ammonia with carbon dioxide to produce ammonium carbonate (NH2CO2NH4), followed by the dehydration of ammonium carbonate to produce urea (NH2CONH2) and water.

2NH3 (g) + CO2 (g) -> NH2CO2NH4 (s) NH2CO2NH4 (s) -> NH2CONH2 (s) + H2O (g)

A 100.0L reaction vessel is charged with 3.4atm of ammonia and 3.2atm of carbon dioxide at 50*C. The vessel is then heated to 150*C.

a) What is the pressure of the vessel after the reaction has gone to completion?

b) If the vessel is then cooled to 15*C, what is the pressure?

c) After the vessel is cooled to 15*C, an aqueous solution is drained from the reaction vessel. What is the molarity of that solution?

d) Industrially, this reaction is often carried out at pressures ranging from 130atm to 260atm and 180*C. Give a plausible reason for these extreme reaction conditions.

Please explain in a detailed way. Thank you for all the help.

Explanation / Answer

a) From charles law P directly proportional to T

Therefore, P1/P2 = T1/T2

P1 = 6.6, P2 = -, T1 = 327K, T2 = 423

Sbstitute the values we get final pressure after reaction P2 = 8.64atm.

b) pressure at 15*C is 5.8atm.

c) Ideal gas equation: PV = nRT

rearrage P = (n/V)RT

P = CRT

C = P/RT

C = 5.88/(0.0821*288)

C = 0.25M

d) According to le chatelier principle when any system is subjected change in concentration, pressure, temperature, volume then the system readjust its equlibrium according the change in T, P, V and C.

The above reaction is a endothermic reaction. So at higher temperatures requre to get the reation done fast with good yields idustrially.

In the forward reaction number of moles decreased. Under higher pressure conditions in the system number of moles increased. So the system moves in a direction where it reduces its number of moles.

under this set of conditions industrially the above reaction requires higher temperature and pressure conditions.

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