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For the reaction A + B → products, the following observations are made: (1) If only the initial concentration of A is doubled, the reaction rate becomes twice its original value. (2) If the initial concentrations of both A and B are doubled together, the reaction rate increases by a factor of 8. The rate law for this reaction is:
- rate = k [A][B]^2
- rate = k [A]^2 [B]^2
- rate = k [A][B]
- rate = k [A]^2 [B]
Correct answer: rate = k [A]^2 [B]
Solution
The correct option indicates that the reaction rate is directly proportional to the square of the concentration of A and linearly proportional to the concentration of B. This is supported by the observations: doubling A alone doubles the rate, while doubling both A and B results in an eightfold increase, consistent with the derived rate law.
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