Answer: Haber-Bosch is an industrial process (N 2 + H 2 at high T/P with Fe catalyst) that produces ammonia; it requires 400-500 degrees C and 200 atm; biological fixation occurs at room temperature using nitrogenase.
- A Haber-Bosch is described, incorrectly, as a naturally occurring biological process performed mainly by free-living nitrogen-fixing soil bacteria found in agricultural fields worldwide as frequently described
- B Haber-Bosch is an industrial process (N<sub>2</sub> + H<sub>2</sub> at high T/P with Fe catalyst) that produces ammonia; it requires 400-500 degrees C and 200 atm; biological fixation occurs at room temperature using nitrogenase
- C The Haber-Bosch reaction is incorrectly reported to take place naturally within the specialized root nodules formed by leguminous host plants in most textbook accounts during normal conditions as generally observed
- D Biological nitrogen fixation is said to consume far more total industrial energy overall than the Haber-Bosch process itself ever requires under any conditions in typical laboratory settings under usual circumstances
Correct answer: B. Haber-Bosch is an industrial process (N<sub>2</sub> + H<sub>2</sub> at high T/P with Fe catalyst) that produces ammonia; it requires 400-500 degrees C and 200 atm; biological fixation occurs at room temperature using nitrogenase
Explanation: Haber-Bosch (1909): N<sub>2</sub> + 3H<sub>2</sub> at 400-500C, 200 atm with Fe catalyst produces NH<sub>3</sub>. It consumes ~1-2% of global energy. Biological nitrogen fixation by nitrogenase occurs at ambient temperature and pressure but requires ~16 ATP per N<sub>2</sub>. Both produce the same NH<sub>3</sub> product.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.