The decomposition of phosphine (PH3) on tungsten at low pressure is a...
Explanation:
Phosphine (PH3) decomposition on tungsten at low pressure is a first-order reaction. This means that the rate of the reaction is directly proportional to the concentration of phosphine.
Surface Coverage:
The surface coverage refers to the number of phosphine molecules that are adsorbed on the surface of the tungsten catalyst. In this case, the surface coverage of phosphine is proportional to its concentration.
Rate of the Reaction:
The rate of the reaction is determined by the rate of decomposition of phosphine. In a first-order reaction, the rate of the reaction is directly proportional to the concentration of the reactant.
Explanation of the Correct Answer:
The correct answer is option 'A' - the rate is proportional to the surface coverage.
The rate of the reaction is determined by the number of phosphine molecules that are adsorbed on the surface of the tungsten catalyst. The more phosphine molecules that are adsorbed, the higher the surface coverage, and the faster the rate of decomposition.
This is because the adsorbed phosphine molecules are in close proximity to each other, allowing for easier collisions and reactions to occur. As a result, the rate of decomposition is directly proportional to the surface coverage of phosphine.
If the surface coverage decreases, the rate of the reaction will also decrease because there are fewer phosphine molecules available for decomposition. This is why the rate is inversely proportional to the surface coverage (option 'B') is incorrect.
The rate of the reaction is also not independent of the surface coverage (option 'C') because, as explained above, the rate is directly proportional to the surface coverage.
The rate of decomposition being slow (option 'D') is not a characteristic of a first-order reaction. The rate of the reaction can be slow or fast, depending on the specific conditions and catalyst used.
The decomposition of phosphine (PH3) on tungsten at low pressure is a...
At low pressure, rate is proportional to the surface coverage and is of first order while at high pressure, it follows zero order kinetics due to complete coverage of surface area.
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.