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A first-order reaction A -> B has a rate constant K = 6.93 * 10⁻³ min⁻¹ at 20 deg C. The temperature coefficient of the reaction is 2 (constant). The half-life of A at 70 deg C is given as 25x/16 min. Find the value of x.
- x = 2
- x = 4
- x = 8
- x = 1
Correct answer: x = 2
Solution
At 20 deg C, t₁/2 = 0.693 / (6.93 * 10⁻³) = 100 min. At 70 deg C, K = 6.93 * 10⁻³ * 32 = 0.22176 min⁻¹, giving t₁/2 = 0.693 / 0.22176 = 25/8 min = 25*2/16 min, so x = 2.
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