Cho hỗn hợp gồm vinyl axetat, metyl axetat và etyl fomat. Đốt cháy hoàn toàn 3,08 gam X, thu được 2,16 gam H2O. Phần trăm số mol của vinyl axetat trong x là

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Cho hỗn hợp gồm vinyl axetat, metyl axetat và etyl fomat. Đốt cháy hoàn toàn 3,08 gam X, thu được 2,16 gam H2O. Phần trăm số mol của vinyl axetat trong x là

A.  25%           B. 27,92%          C.72,08%           D. 75%

Giải: vinyl axetat: CH3COOCH=CH2; metyl axetat: CH3COOCH3; etyl fomat: HCOOC2H5.

Bài này không khó chỉ lừa học sinh tí thôi, nếu viết theo công thức ở trên là 3 chất, nhưng nếu T viết dạng khác thì chỉ còn 2 chất:

vinyl axetat: C4H6O2 ,x mol; và 2 đứa song sinh: C3H6O2 y mol.

Ta có hệ:

ü 86x+74y=3,08

ü 6x+6y=2nH2O=0,24

Giải hệ trên ta được: x=0,01, y=0,03

Vậy phần tram số mol là 0,01/0,04=0,25=25%.

Đáp án A.


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