问题 问答题

某化学兴趣小组的同学利用如图所示实验装置进行实验(图中a、b、c表示止水夹).

请按要求填空

(1)如何检查B装置的气密性______

(2)A、C、E相连后的装置可用于制取Cl2并进行相关的性质实验.

①若在丙中加入适量水,即可制得氯水.将所得氯水分成两份,进行I、II两个实验,实验操作、现象结论如下:

实验

序号

实验操作现象结论
I将氯水滴入品红溶液溶液褪色Cl2与水反应的产物有漂白性
II氯水中加入NaHCO3粉末有无色气泡产生Cl2与水反应的产物具有较强的酸性
请你评价实验I、II的结论是否合理?若不合理,请说明理由.______

②请利用上述装置设计一个简单的实验,验证C厂和B广的还原性强弱(分别指出甲、乙、丙中盛装的试剂、实验现象及结论)______

(3)B、D、E装置相连后,在B中盛装浓硝酸和铜片(放在有孔塑料板上),可制得NO2并进行有关实验.

①B中发生反应的化学方程式为______

②欲用D装置验证NO2与水的反应(此时c处于关闭状态),其操作步骤为先关闭止水夹______再打开止水夹______,使烧杯中的水进入试管丁的操作是______.

③试管丁中的NO2与水充分反应后,若向试管内缓缓通入一定量的O2,直至试管全部充满水,则所得溶液中溶质的物质的量浓度是______ (气体按标准状况计算).

答案

(1)装置气密性检查的原理一般是通过压强差产生的明显现象来判断,所以用止水夹夹住橡皮管,向长颈漏斗中加水,若试管中液面不再改变,则装置的气密性良好.

故答案为:用止水夹夹住橡皮管,向长颈漏斗中加水,若试管中液面不再改变,则装置的气密性良好.

(2)①浓盐酸有挥发性,所以制取的氯气中含有氯化氢气体,氯化氢极易溶于水生成盐酸,盐酸和品红溶液不反应,但和碳酸氢钠反应生成二氧化碳,氯气和水反应也生成盐酸,所以实验Ⅱ无法判断是哪部分的盐酸,所以不合理.

故答案为:实验Ⅰ结论合理,实验Ⅱ结论不合理,因为制取的氯气中含有氯化氢气体,氯化氢溶于水后能与碳酸氢钠粉末反应产生气泡;

②实验室用二氧化锰和浓盐酸反应制取氯气,分液漏斗只能盛装液体,所以甲装浓盐酸,乙盛装二氧化锰;丙是用来检验氯气的性质,所以盛装溴化钠溶液;二氧化锰和浓盐酸反应生成黄绿色的氯气,所以会看到烧瓶中有黄绿色的气体生成;氯气和溴属于同一主族的元素,随着原子序数的增大,非金属性逐渐减弱,所以氯气能置换出溴化钠中的溴,试管内溶液由无色变为橙色,由此证明氯气的氧化性强于溴,则证明Br-的还原性强于Cl-

故答案为:在甲、乙、丙中分别装入浓盐酸、二氧化锰、溴化钠溶液,烧瓶中有黄绿色气体生成,试管中溶液由无色变为橙色,证明氯气的氧化性强于溴,则证明Br-的还原性强于Cl-

(3)①铜和浓硝酸反应生成硝酸铜、二氧化氮和水,方程式为:Cu+4HNO3(浓)=Cu(NO32+2NO2↑+2H2O.

故答案为:Cu+4HNO3(浓)=Cu(NO32+2NO2↑+2H2O.

②若二氧化氮能和水反应,则烧杯内气体的压强会减小,小于外界大气压,烧杯中的溶液会倒流于试管丁,所以先关闭止水夹 ab再打开止水夹 c,使烧杯中的水进入试管丁.

故答案为:ab;c;双手紧握试管丁使试管中气体逸出,二氧化氮与水接触后即可引发烧杯中的水倒流于试管丁.

③设容器的体积为VL,所以二氧化氮气体的物质的量为n=

VL
22.4L/mol
,二氧化氮和氧气、水反应生成硝酸,所以溶质是硝酸.

设生成硝酸的物质的量为xmol;

4NO2+O2+2H2O=4HNO3

4mol          4mol

VL
22.4L/mol
  xmol

x=

VL
22.4L/mol

C=

n(HNO3)
V
=
VL
22.4L/mol
VL
=0.045mol/L

故答案为:0.045mol/L.

选择题
完形填空
Recently, I experienced a wonderful lesson in how little things still mean a lot. My home is on the Big Island of Hawaii. About a month ago, when I   36  my car and was about to drive off, I
  37  at the roadside. A piece of paper   38  my eye. I picked it up and read it   39 . Instantly, I was grateful that I had done that.
The form turned out to be a receipt from the State Motor Vehicle Division, documenting the owners’   40  of their Vehicle’s Registration fees. Quickly, I put myself in their shoes and  __41 : no one would throw this away, especially   42  it was current. I also looked over the form for contact or any personal   43 , perhaps a license tag or telephone number. But that seemed __44 . The form had been blown by the wind, so   45  would I find the owners? Had it been lying there for a few minutes or a week? So I checked the date and   46  the names of the owners , who must  47  in our town. I believed that the best and easiest step to take was to put the form in a(n)  48  addressed to the couple and mail it by post. Further, I imagined that if I had posted the receipt to a wrong   49  , how frantic(慌乱的)I’d be. But it was much   __50_  to attempt to return it than to leave them angry, upset , etc. over the   51  , so I did as I thought. My hunch(预感) was right. On the weekend, a happy couple   52  my house and brought me a big gift. They said they had panicked(恐慌)and   53  the receipt madly everywhere before giving up. Without it they would have to   54  another 8,000. It felt great to know I’d helped someone avoid a major trouble by doing   55  that at first glance seemed minor.
小题1:
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小题2:.
A.lay downB.flew downC.glanced downD.jumped down
小题3:.
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小题15:.
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小题16:
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小题17:.
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A.took awayB.searched forC.looked atD.asked about
小题19:
A.earnB.save C.borrowD.spend
小题20:.
A.anythingB.nothingC.somethingD.everything