Fertilizer analysis: A fertilizer is reported to contain 82% nitrogen (N) by mass. Which common nitrogen fertilizer could match approximately 82% N content?

Introduction / Context:Nutrient analysis of fertilizers is typically expressed as mass percent of the nutrient element. For nitrogenous fertilizers, knowing the theoretical nitrogen fraction from chemical formulae allows quick identification. This question tests whether you can connect a stated 82% nitrogen content to the correct fertilizer material used widely in agriculture and ammonia-based industries.

Given Data / Assumptions:

• Labeled nitrogen content is 82% by mass.
• Consider common fertilizers: anhydrous ammonia, urea, ammonium nitrate, and blends like CAN.
• Assume pure materials (no inert fillers or coatings).

Concept / Approach:The mass percent of an element in a compound is calculated as (mass of the element in the formula / molar mass of the compound) * 100. For NH3, molar mass = 17 (N = 14; H = 3); percent N = 14/17 ≈ 82.35%. Urea contains about 46% N; ammonium nitrate contains about 35% N; calcium ammonium nitrate is lower still due to added limestone. Therefore, only anhydrous ammonia matches 82% N closely.

Step-by-Step Solution:

Verification / Alternative check:Any fertilizer handbook lists NH3 at ~82% N, urea ~46% N, ammonium nitrate ~33–35% N, and CAN ~26–28% N depending on grade. The given value can only correspond to anhydrous ammonia among the options.

Why Other Options Are Wrong:

• Urea: about 46% N, not close to 82%.
• Ammonium nitrate: roughly 35% N.
• Calcium ammonium nitrate: lower than ammonium nitrate due to limestone.
• None of these: incorrect because NH3 fits.

Common Pitfalls:Confusing percent nitrogen with percent ammonia; remembering that “82” is a quick mnemonic for anhydrous ammonia.

Final Answer:Anhydrous ammonia (liquid NH3).