Urea, a commonly used nitrogen-based fertiliser, is prepared by the reaction between ammonia and ______. |
carbon dioxide hydrogen oxygen sulphur |
carbon dioxide |
The correct answer is option 1. carbon dioxide. The synthesis of urea involves the reaction between ammonia (\(NH_3\)) and carbon dioxide (\(CO_2\)). This chemical process is known as the Bosch–Meiser urea process. Here's an overview of the reaction and the process: 1. Formation of Ammonium Carbamate: Ammonia gas (\(NH_3\)) is allowed to react with carbon dioxide (\(CO_2\)) in the presence of water (\(H_2O\). The initial reaction involves the formation of ammonium carbamate (\(NH_2COONH_4)). \[ 2NH_3 + CO_2 + H_2O \rightarrow NH_2COONH_4 \] 2. Formation of Urea: The ammonium carbamate formed in the first step undergoes further chemical rearrangement to yield urea (\(CO(NH_2)_2\)). \[ NH_2COONH_4 \rightarrow CO(NH_2)_2 + H_2O \] The overall reaction can be represented as follows: \[ 2NH_3 + CO_2 \rightarrow CO(NH_2)_2 + H_2O \] 4. Process Conditions: The synthesis typically occurs under high pressure and elevated temperatures to favor the formation of urea. A catalyst, often a compound containing manganese, is used to enhance the reaction rate. The urea formed is then purified, often through processes such as crystallization, to obtain the final product in a solid form suitable for use as a fertilizer. In summary, urea is prepared by reacting ammonia with carbon dioxide in a series of chemical steps known as the Bosch–Meiser urea process. The resulting urea is a valuable nitrogen fertilizer widely used in agriculture. |