高中化學有機的題目

設該飽和脂肪酸的分子式為CnH2n+1COOH。

CnH2n+1COOH+ CH3OH → Cn­H2n+1COOCH3+H2O
故知有機物X為Cn­H2n+1COOCH3。

Cn­H2n+1COOCH3+ C2H5NH2→ C­nH2n+1­CONHC2H5+CH3OH

CnH2n+1COOH的分子量 = 12x(n+1) + 1x(2n+4) + 16x2= 14n + 46
C2H5NH2的分子量 = 12x2 + 1x7 + 14 = 45

從方程式可知，Cn­H2n+1COOCH3的莫耳數 = C2H5NH2的莫耳數
7.4 / (14n + 46) = 4.5 / 45
7.4 / (14n + 46) = 0.1
14n + 46 = 74
14n = 28
n = 2

該脂肪酸是 C2H5COOH。