The rate of a chemical reaction remains invariant to reactant concentrations for a _________________ reaction?
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Answer: A. Zero order
Explanation
Zero-order reactions feature reaction rates that remain completely invariant to changes in reactant concentrations. The rate law for a zero-order process depends only on the rate constant, ignoring concentration terms. Reactant depletion does not slow down zero-order reactions until reactants are nearly fully exhausted. Reaction order mathematically describes how reactant concentration changes affect the overall speed of reaction. Zero-order kinetics typically occur on heavily saturated catalytic surfaces where active sites are full. The rate constant units for zero-order reactions are concentration divided by units of time.
Heterogeneous catalytic reactions often operate under zero-order conditions at high reactant partial pressures. Photochemical reactions frequently demonstrate zero-order kinetics when light absorption is the limiting factor. Engineers account for zero-order behavior when designing specific types of gas-solid catalytic reactors. Option B describes third-order reactions where the rate depends on the cube of reactant concentrations. Option C describes consecutive reaction sequences involving multiple intermediate chemical steps in series. Option D is incorrect because zero-order correctly answers the question regarding concentration independence.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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