问题 填空题

已知α-氨基丙酸的结构简式为,它可与NaOH反应生成α-氨基丙酸钠,其化学式为C3H6O2NNa,又知味精的主要成分是谷氨酸一钠,它可以由谷氨酸与与NaOH反应生成,其结构简式为

已知它具有下列相关性质:

①常态下为白色晶体,含有一分子结晶水,无气味,易溶于水,有肉类鲜味;②在碱性条件下会生成似咸非咸、似涩非涩的谷氨酸二钠,鲜味降低;③在150℃时失去结晶水,在210℃时生成对人体有害的焦谷氨酸盐,并在270℃左右进一步分解.根据以上信息填空:

(1)α-氨基丙酸与氢氧化钠反应的化学方程式为______;

(2)写出谷氨酸二钠结构简式:______;

(3)使用味精适宜的条件是______.

答案

(1)由题目中给出的信息可知反应物是CH3CHNH2COOH和NaOH生成物是CH3CHNH2COONa和H2O,所以方程式是:CH3CHNH2COOH+NaOH═CH3CHNH2COONa+H2O;

(2)谷氨酸二钠结构简式,是通过图示计算出钠原子、氧原子、碳原子、氮原子、氢原子个数,所以结构简式是NaOOCCHNH2CH2CH2COONa,即

(3)味精在210℃时生成对人体有害的焦谷氨酸盐,所以使用味精适宜的条件是在较低温度下.

故答案为:(1)CH3CHNH2COOH+NaOH═CH3CHNH2COONa+H2O;

(2)

(3)在较低温度下.

单项选择题

The Erie Canal was the first important national waterway built in the US. It crossed New York from Buffalo on Lake Erie Troy to Albany on the Hudson River. It joined the Great Lakes with the Atlantic Ocean. The canal served as a route over which industrial goods could flow into the west, and materials could pour into the east. The Erie Canal helped New York develop into the nation’s largest city.

The building of the canal was paid for entirely by the state of New York. It cost $ 7 143 789, but it soon gained its price many times over. Between 1825, when the canal was opened, and 1882, when toll charges were stopped, the state collected $121 461 891.

For a hundred years before the Erie was built, people had been talking about a canal which could join the Great Lakes and the Atlantic Ocean. The man who planned the Erie Canal and carried the plan through was De Witt Clinton. Those who were against the canal laughingly called it "Clinton’s Ditch". Clinton talked and wrote about the canal and drew up plans for it. He and Governor Morris went to Washington in 1812 to ask for help for the canal, but they were unsuccessful.

Clinton became governor of New York in 1817, and shortly afterwards, on July 4, 1817, broke ground for the canal in Rome, N. Y. The first part of the canal was completed in 1820. As the canal grew, towns along its course developed fast. The length of the canal is 363 miles.

Which of the following is true according to the passage().

A. The Erie Canal brought profits of over $ 114 000000

B. It’s 363 miles from the Great Lakes to the Atlantic Ocean.

C. The West was more advanced than the East when the canal was built.

D. Many other states helped New York built the canal.

填空题