Fertilizer chemistry – structural formula of urea Identify the correct structural formula for urea used in nitrogenous fertilizers.

Introduction / Context:
Urea is the world’s most widely used solid nitrogen fertilizer, valued for its high nitrogen content (~46% N) and handling properties. Recognizing its chemical structure is basic to understanding hydrolysis, volatilization risks, and soil interactions.

Given Data / Assumptions:

• Urea forms via reaction of ammonia with carbon dioxide under high pressure to make ammonium carbamate followed by dehydration.
• The structure is a carbonyl flanked by two amide groups.
• No ions are present in the final solid; it is a neutral organic molecule.

Concept / Approach:
The correct condensed formula is NH2–CO–NH2, indicating a central carbonyl (C=O) with two terminal amine groups. Alternative strings given either misplace atoms, imply different functional groups, or represent unreal species at standard conditions. The correct identification guides understanding of enzymatic hydrolysis by urease to ammonium and bicarbonate in soils.

Step-by-Step Solution:

Verification / Alternative check:
Infrared spectra show a strong carbonyl band and N–H stretches consistent with the diamide structure.

Why Other Options Are Wrong:

• NH3CO.CH3 / NH.CO2.NH / NH3.CO2.NH3: Not urea; these imply other species or unstable adducts.

Common Pitfalls:
Confusing ammonium carbamate (an intermediate) with urea; the former contains ionic NH4+ and HCOO−-like features prior to dehydration.

Final Answer:
NH2.CO.NH2