For a reaction P + Q R , the time required for 87.5 % completion of P is three times its half-life. Also, a plot of 1 [ Q ] versus time gives a straight line with a positive slope. If the rate constant for the reaction is 2 10⁻³ M ⁻² s ⁻¹ ,

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For a reaction P + Q R , the time required for 87.5 % completion of P is three times its half-life. Also, a plot of 1 [ Q ] versus time gives a straight line with a positive slope. If the rate constant for the reaction is 2 10⁻³ M ⁻² s ⁻¹ , the initial rate of the reaction when [ P ]₀ = 0.1 M and [ Q ]₀ = 0.2 M is x 10⁻⁶ M s ⁻¹ . The value of x is _______

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Correct answer: 8

For reactant P , the time for 87.5 % completion means 12.5 % of P remains. Amount remaining = 100 2^3 = 12.5 % This corresponds to exactly 3 half-lives. Since t_ 87.5 % = 3 t_ 1/2 , the half-life is independent of the initial concentration, which is a characteristic of a first-order reaction. Thus, the order with respect to P is 1 . For reactant Q , the plot of 1 [ Q ] versus time is a straight line with a positive slope. The integrated rate law for a second-order reaction is 1 [ Q ] = 1 [ Q ]₀ + kt . Thus, the ord

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