１題化學題 - Ans.fyi 參考答案

１題化學題

2008-01-12 4:21 am

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1.科學家從蛋白質的水解液中分離出一種分子中只有1個氮原子的氨基酸,進行分析時,從1.995g該氨基酸中得到168mL(標況)的氮氣;另取26.6g該氨基酸恰好與1.6moL/L的NaOH溶液250mL完全反應,求該氨基酸的摩尔質量并試確定氨基酸的結構簡式.

回答 (1)

用戶221652

2008-01-15 8:29 pm

✔ 最佳答案

In standard condition (25C, 1bar) molar volume of a gas is 24.8 dm3/mol

volume of N2 = 168mL = 0.168 dm3
-> # of moles of N2 = 0.168/24.8 mole = 0.00677 mole
-> # of moles of N = 0.00677*2 = 0.01354 mole
-> # of moles of the amino acid = 0.01354 mole
-> Molar mass of the amino acid = 1.995/0.01354 g/mol = 147.34 g/mol

Amino acid is Glutamic acid.

To further confirm it,

# of moles of NaOH = 250/1000 * 1.6 mol/L = 0.4 mol
-> # of moles of COOH = 0.4 mol

Glutamic acid has 2 COOH groups
# of moles of COOH in 26.6g = 26.6/147.34 *2 ~ 0.4 mol

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