问题 填空题

实验室里迅速制备少量氯气可利用以下反应:

______KMnO4+______ HCl═______ KCl+______ MnCl2+______ Cl2↑+______ H2O

(1)请配平上述化学方程式,并在上面用“双线桥法”标明电子转移的方向和数目:

(2)该反应的氧化产物是______,KMnO4发生______反应.

(3)HCl在上述反应中显示出来的性质是______.

A.氧化性        B.还原性       C.酸性       D.碱性

(4)用该浓盐酸制得了标况下560mlCl2,则被氧化的HCl为______mol,需要KMnO4的质量______g,转移电子数为______.

答案

(1)反应中HCl→Cl2,氯元素化合价由-1价升高为0价,共升高2价,KMnO4→MnCl2,Mn元素化合价由+7价降低为+2价,共降低5价,化合价升降最小公倍数为10,故KMnO4系数为2,故Cl2系数为5,根据Mn元素守恒可知MnCl2系数为2,根据K元素守恒可知KCl系数为2,根据Cl元素守恒可知HCl系数为16,根据H元素可知H2O的系数为8,配平后方程式为:

2KMnO4+16HCl═2KCl+2MnCl2+5Cl2↑+8 H2O,用“双线桥法”标明电子转移的方向和数目为:

故答案为:2、16、2、2、5、8;

(2)反应中HCl→Cl2,氯元素化合价由HCl中-1价升高为Cl2中0价,Cl2是氧化产物;

反应KMnO4→MnCl2,Mn元素化合价由+7价降低为+2价,KMnO4是氧化剂,发生还原反应;

故答案为:Cl2;还原;

(3)由方程式可知,反应后KCl、Cl2中含有氯元素,KCl中氯元素化合价为-1价,Cl2中氯元素化合价为0价,说明反应中HCl表现酸性、还原性;

故选BC;

(4)560mlCl2的物质的量为

0.56L
22.4L/mol
=0.025mol,被氧化的HCl为生成Cl2,根据氯元素守恒可知被氧化的HCl为0.025mol×2=0.05mol;

根据2KMnO4+16HCl═2KCl+2MnCl2+5Cl2↑+8 H2O可知,生成0.025molCl2,需要KMnO4的物质的量为:0.025mol×

2
5
=0.01mol,质量为0.01mol×158g/mol=1.58g;

反应中HCl→Cl2,氯元素化合价由HCl中-1价升高为Cl2中0价,故转移电子物质的量为0.025mol×2=0.05mol,转移电子数目为0.05mol×NAmol-1=0.05NA

故答案为:0.05;1.58;0.05NA

阅读理解

A gentleman stopped his car at the door of a flower shop. He planned to order flowers and asked the shopkeeper to deliver them to his mother, who was far away in his hometown.

The gentleman saw a little girl crying on the road before he entered the shop. The gentleman asked her: “Why are you crying?”

“I want to buy a rose for my mother, but I haven’t got enough money,” said the girl.

The gentleman took the girl’s hand and entered the flower shop. He first ordered the bouquet (花束) for his mother and bought a rose for the girl.

When he was walking out of the shop, the gentleman asked the girl if she would like a ride home.

“Will you really drive me home?” she asked.

“Of course,” the gentleman replied.

“Then drive me to my mother. But the place where my mother lives is very far.”

The gentleman drove along the mountain road and finally came to the cemetery (墓地).

The little girl put the flower onto a new grave (坟墓). In order to send a rose to her mother who had died a month before, she had gone on a very long journey.

The gentleman drove the girl to her home and then returned to the flower shop. He cancelled(取消)the bouquet and bought a big bunch (束) of fresh flowers instead. He drove directly to his mother’s home, a five-hour drive from here. He would send the flowers to his mother in person.

小题1:The word “deliver” in Paragraph 1 means “______________”.

A.give

B.take

C. send

D.bring小题2:Why was the little girl crying?

A.Because her mother died.

B.Because she lost her money.

C.Because she lost her way home.

D.Because she couldn’t afford a rose.小题3:The little girl asked the gentleman to drive her ______________.

A.to her home

B.to her school

C.to a cemetery

D.to a mountain小题4:We can tell from the story that ___________.

A.The little girl loves her mother very much

B.The gentleman doesn’t care about his mother

C.The little girl’s mother lives far away from her home

D.The gentleman’s mother passed away a month ago

名词解释