Question

Urea,NH2CONH2, is manufactured from ammonia and carbon dioxide according to the following equation: 2 NH3(g) +CO2 (g) ->NH2CONH2 (aq)+H2O (l)

What volume of ammonia gas at 25 o C and 1.5 atm is needed to make 1500g of urea?

Please explain!

Answer 1

Given balanced reaction is 2 NH3(g) +CO2 (g) ->NH2CONH2 (aq)+H2O (l)

Molar mass(g/mole)              17           44             60                    18

Calculation of number of moles of Urea:

Number of moles , n = mass/MOlar mass

                              = 1500g / 60(g/mole)

                              = 25 moles

From the balanced reaction ,

1 mole of urea formed from 2 moles of ammonia

25 moles of urea formed from (25*2)/1 = 50 moles of NH3

We know that ideal gas equation is PV = nRT

Where

T = Temperature = 25oC = 25+273 = 298 K

P = pressure = 1.5 atm

n = No . of moles = 50 moles

R = gas constant = 0.0821 L atm / mol - K

V= Volume of the ammonia gas = ?

Plug the values we get

V = (nRT)/P

   = ( 50mole * 0.0821L atm/mol-K*298K) / 1.5 atm

   = 815.5 L