Question Video: Completing the Equation for the Formation of Urea from Ammonia Chemistry

The following equation shows the production of urea, CO(NH₂)₂, a fertilizer often made at plants where the Haber process is running: 𝑋NH₃ + Y ⟶ CO(NH₂)₂ + Z. Which of the following replaces 𝑋, Y, and Z in the equation? [A] 𝑋: 2, Y: CO, Z: H₂ [B] 𝑋:2, Y: HNCO, Z: H₂O [C] 𝑋:1, Y: (NH₄)₂CO₃, Z: H₂ [D] 𝑋:1, Y: H₂CO₃, Z: H₂O [E] 𝑋: 2, Y: CO₂, Z: H₂O

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Video Transcript

The following equation shows the production of urea, CO(NH2)2, a fertilizer often made at plants where the Haber process is running: 𝑋NH3 plus Y reacts to produce CO(NH2)2 plus Z. Which of the following replaces 𝑋, Y, and Z in the equation? (A) 𝑋 is two, Y is CO, Z is H2. (B) 𝑋 is two, Y is HNCO, and Z is H2O. (C) 𝑋 is one, Y is (NH4)2CO3, and Z is H2. (D) 𝑋 is one, Y is H2CO3, and Z is H2O. Or (E) 𝑋 is two, Y is CO2, and Z is H2O.

In this question, we need to complete the equation for the production of urea from ammonia and an unidentified molecule. Ammonia is a valuable substance made during the Haber process. It is an important nitrogenous fertilizer that can be used to generate other fertilizers such as urea. Carbon dioxide is reacted with ammonia to produce urea. So we can already tell that the answer will be option (E). But for completeness, let’s balance the equation and work out what unknowns 𝑋 and Z represent.

Let’s tally how many of each atom we have on the reactants and products side. If we start with nitrogen atoms, we can see that there is only one on the reactants side but two on the products. If we have two equivalents of ammonia, the nitrogen atoms are now balanced. To make the overall equation balanced, we need two hydrogens atoms and one oxygen. So an equivalent of water would balance the equation. We can therefore see that two equivalents of ammonia react with one equivalent of carbon dioxide to produce one equivalent of urea and one equivalent of water.

Therefore, the correct answer is (E): 𝑋 is two, Y is CO2, and Z is H2O.