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At 518°C, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of 363 Torr, was 1.00 Torr s−1 when 5% had reacted and 0.5 Torr s−1 when 33% had reacted. The order of the reaction is:
- 1
- 2
- 3
- 0
Correct answer: 2
Solution
Remaining pressures: at 5% reacted P = 0.95(363) = 344.9 Torr (rate 1.00); at 33% reacted P = 0.67(363) = 243.2 Torr (rate 0.50). For rate = k P^n, 1.00/0.50 = (344.9/243.2)^n gives 2 = 1.418^n, so n ~ 2. The reaction is second order.
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