化學問題(是英文的)－jpjzhf9的部落格

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化學問題(是英文的)

發問:

A white powder, consisting of a simple mixture of tartaric acid (C4H6O6) and citric acid (C6H8O7) was analysed to determine the elemental composition. Combustion of a 431.9-mg sample produced 559.2 mg of CO2 and 159.4 mg of H2O.Use atomic masses: C 12.011; H 1.00794; O 15.9994.Calculate the %... 顯示更多 A white powder, consisting of a simple mixture of tartaric acid (C4H6O6) and citric acid (C6H8O7) was analysed to determine the elemental composition. Combustion of a 431.9-mg sample produced 559.2 mg of CO2 and 159.4 mg of H2O. Use atomic masses: C 12.011; H 1.00794; O 15.9994. Calculate the % citric acid, by mass, in the sample. 請幫幫忙吧...感激不盡更新: 是要問怎麼算....

最佳解答:

設citric acid為 X mg tartaric acid=(431.9-X) mg 由citric acid 生成CO2 為A mg 由tartaric acid生成CO2=(559.2-A ) mg 由citric acid 生成H2O為B mg 由tartaric acid 生成H2O=(159.4-B) mg 2C6H8O7 + 9O2 --->12CO2 + 8H2O 384 ---> 528 144 X ---> A B 384/X = 528/A 384A=528X A=1.375X 2C4H6O6 + 5 O2 ---> 8CO2 + 6H2O 300 ---> 352 108 (431.9-X) --->559.2-A 159.4-B 300/(431.9-X) = 352/(559.2-A) 352(431.9-X) = 300(559.2-A) A=1.375X代入 352(431.9-X) = 300(559.2-1.375X) 152028.8-352X = 167760-412.5 60.5X = 15731.2 X=260.02 The % citric acid, by mass=260.2/431.9=0.602=60.2% 同法可由生成水B算出相同答案驗算此分稀數據是正確的 2009-01-18 10:31:33 補充：此題並不難但是打字排版對超過六十歲老人家可就難了

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分析一種白色粉末的元素成分，該樣品為酒石酸(C4H6O6) 與檸檬酸 (C6H8O7) 的混合物。燃燒該樣品431.9毫克，可產生559.2 毫克的二氧化碳以及159.4毫克的水，利用原子量: C 12.011; H 1.00794; O 15.9994 計算檸檬酸(C6H8O7) 在此樣品中的重量百分比。 2009-01-19 13:11:35 補充：嘖嘖...原來你不是要問翻譯呀! 白白浪費時間。428DFA428D9FA6F8