For the reaction X → Y, doubling the concentration of ‘X’ causes the reaction rate to increase fourfold. If the rate follows a proportionality of Cx n, what is the numerical value of „n‟?
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Answer: C. 4
Explanation
Reaction rate is proportional to reactant concentration raised to the reaction order power. Doubling reactant concentration increases the overall reaction rate by a factor of four. Since two raised to the power of two equals four, the reaction order equals two. Reaction order is an empirical exponent determined experimentally from concentration rate data. Elementary reactions have molecularity matching their stoichiometric reaction orders. Power law rate expressions describe how operating variables affect chemical reaction rates.
Determining reaction orders is a fundamental step in chemical reactor design and kinetics. Industrial reactor sizing depends entirely on knowing accurate reaction orders and rate constants. Catalyst testing protocols measure reaction rates across varying concentrations to find orders. A reaction order of one quarter would predict a much smaller rate increase. A reaction order of sixteen would require an astronomical rate increase for doubled concentration. The numerical value of n represents the exponent two, matching the second-order rate.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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