问题 填空题

化学小组采用类似制乙酸乙酯的装置(如下图),用环己醇制备环己烯。

已知:

 密度(g/cm3)熔点(℃)沸点(℃)溶解性
环己醇0.9625161能溶于水
环己烯0.81-10383难溶于水

(1)制备粗品

将12.5 mL环己醇加入试管A中,再加入1 mL浓硫酸,摇匀后放入碎瓷片(防止爆沸),缓慢加热至反应完全,在试管C内得到环己烯粗品。

①导管B除了导气外还具有的作用是________。

②试管C置于冰水浴中的目的是______________________________。

(2)制备精品

①环己烯粗品中含有环己醇和少量酸性杂质等。加入饱和食盐水,振荡、静置、分层,环己烯在________层(填“上”或“下”),分液后用________(填入编号)洗涤。

A.KMnO4溶液         B.稀H2SO4            C.Na2CO3溶液

②再将环己烯按上图装置蒸馏,冷却水从________口进入(填“g”或“f”)。蒸馏时要加入生石灰,其目的是_____________________________________。

③收集产品时,控制的温度应在________左右,实验制得的环己烯精品质量低于理论产量,可能的原因是________。

A.蒸馏时从70 ℃开始收集产品

B.环己醇实际用量多了

C.制备粗品时环己醇随产品一起蒸出

(3)以下区分环己烯精品和粗品的方法,合理的是________。

A.分别加入酸性高锰酸钾溶液

B.分别加入用金属钠

C.分别测定沸点

答案

(9分)(1)①冷凝 ②防止环己烯的挥发

(2)①上 C ②g 除去水分 ③83 ℃ C         (3)BC

题目分析:(1)由于生成的环己烯的沸点为83℃,要得到液态环己烯,导管B除了导气外还具有冷凝作用,便于环己烯冷凝;由于环己烯沸点低,易挥发,所以冰水浴的目的降低温度,防止环己烯的挥发。

(2)①环己烯的密度小于水的,不溶于水,所以在上层;由于分液后环己烯粗品中还含有少量的酸和环己醇,联想制备乙酸乙酯提纯产物时用饱和Na2CO3溶液洗涤可除去酸和醇,所以选择的水碳酸钠溶液。不能用酸性高锰酸钾,否则会氧化环己烯,答案选C。生石灰具有吸水性,所以蒸馏时要加入生石灰的目的是除去水分。

②冷却水的流向和气体的流向是相反的,因此冷却水从g口进入,f口出来。

③收集时,只要液体温度达到环己烯的沸点,能把其蒸馏出来就可以了,温度太低蒸馏不出。温度太高,易导致反应温度过高而碳化。因此根据环己烯的沸点可知,一般控制在83℃左右;,实验制得的环己烯精品质量低于理论产量,这说明反应物的转化率低,因此可能的原因是制备粗品时环己醇随产品一起蒸出,答案选C。

(3)区别粗品与精品可加入金属钠,观察是否有气体产生,若无气体,则是精品,混合物没有固定的沸点,而纯净物有固定的沸点,通过测定环己烯粗品和环己烯精品的沸点,可判断产品的纯度,因此答案选BC。

点评:本题以有机合成为载体综合考查了实验室制环己烯的知识和醇、烃的性质,考查了学生综合运用实验的能力,属于中等难度的试题。答题时注意把握实验原理和方法,特别是实验的基本操作,学习中注意积累。

阅读理解

It’s just a small, white envelope stuck among the branches of our Christmas tree. No name, no address. It has peeked through the branches of our tree for the past 10 years.

It all began because my husband Mike hated Christmas. He didn’t hate the true meaning of Christmas, but the commercial aspects of it; overspending, running around at the last minute to get a tie for Uncle Harry and powder for Grandma…

Knowing he felt this way, I decided one year to bypass the usual shirts, sweaters, ties and so forth. I reached for something special for Mike. The inspiration came in an unusual way.

Our son Kevin, at 12 that year, was wrestling at the junior level at the school he attended and before Christmas, there was a non-league match against a team sponsored by an inner-city church, mostly black.

As the match began, I was alarmed to see that the other team was wrestling without headgear to protect a wrestler’s ears. They obviously could not afford.

Mike shook his head sadly, “I wish just one of them could have won,” he said. “They have a lot of potential, but losing like this could take the heart right out of them.”

Mike loved kids—all kids—and he knew them, having coached little league football, baseball and lacrosse. That’s when the idea for his present came.

That afternoon, I went to a local sporting goods store and bought an assortment of wrestling headgear and shoes and sent them anonymously to the inner-city church.

On Christmas Eve, I placed the envelope on the tree, the note inside telling Mike what I had done and that this was his gift from me. His smile was the brightest thing about Christmas that year. For each Christmas, I followed the tradition.

The envelope became the highlight of our Christmas. It was always the last thing opened on Christmas morning and our children, ignoring their new toys, would stand with wide-eyed anticipation as their dad lifted the envelope from the tree to reveal its contents.

The tradition has grown and someday will expand even further with our grandchildren standing around the tree with wide-eyed anticipation watching as their fathers take down the envelope. Mike’s spirit, like the Christmas spirit, will always be with us.

小题1:Which of the following is the best title for the passage?

A.Precious Present

B.Christmas Gift

C.The Small White Envelope

D.The Good Old Tradition小题2:Why did Mike hate Christmas according to the passage?

A.He didn’t like the true meaning of Christmas

B.He didn’t like people spending too much money on presents

C.He hated buying presents for Uncle Harry and Grandma

D.He didn’t want to receive gifts like shirts, sweaters or ties.小题3:Which is the closest meaning to the underlined phrase “take the heart right out of them”?

A.make them excited

B.make them inspired

C.make them lose confidence

D.make them kill themselves小题4:Why was his smile the brightest thing about Christmas that year? ( paragraph 9)

A.He received some sporting goods

B.He found a potential wrestling team

C.His son won the wrestling match

D.His wife sent presents to those poor kids小题5:What can we infer from the passage?

A.The tradition of sending presents will pass from generation to generation.

B.The children were eager to get their new toys ignoring the envelope.

C.With the presents, the poor kids will surely win the match one day.

D.Mike’s spirit, like the Christmas spirit, will always be with us.

多项选择题