Một bình kín chứa 3,584 lít một ankan (ở 0oC và 1,25atm). Đun nóng để xảy ra phản ứng cracking, rồi đưa nhiệt độ bình về 136,5oC thì áp suất đo được là 3atm. Hiệu suất của phản ứng crackinh là :

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