问题 问答题

已知:MnO2+4HCl(浓)

MnCl2+Cl2↑+2H2O请用下图装置设计一个实验,证明Cl2的氧化性比I2的氧化性强.

请回答下列问题:

(1)若气流从左到右,则上述仪器的连接顺序为______.(用字母表示)

(2)证明Cl2 比I2的氧化性强的实验现象是______,反应的离子方程式是______.

(3)若要证明Cl2的氧化性比Br2强,则需做的改动是______

(4)你认为此实验的整体设计是否完善?______.

若不完善,请说明理由并提出你的改进方案.______.

答案

(1)制取氯气的装置为:DEF,氯气氧化碘离子的实验装置为:BA,导管要长进短出,故答案为:DEFBA;

(2)氯气能将碘离子氧化为碘单质,即2I-+Cl2=I2+2Cl-,碘遇淀粉变蓝色,证明Cl2比I2的氧化性强,故答案为:装置①中KI-淀粉溶液出现蓝色;2I-+Cl2=I2+2Cl-

(3)氯气能将溴离子氧化为单质,可以证明氯气的氧化性强于溴,所以将装置①中KI-淀粉溶液改为NaBr溶液即可证明,故答案为:将装置①中KI-淀粉溶液改为NaBr溶液;

(4)氯气是有毒气体,反应后不能直接排入到空气中,必须进行尾气处理,可在①的装置后连接一个盛有氢氧化钠溶液的烧杯,吸收未反应完的氯气,以免污染空气,故答案为:不完善;因氯气是有毒气体,反应后不能直接排入到空气中,可在①的装置后连接一个盛有氢氧化钠溶液的烧杯,吸收未反应完氯气,以免污染空气.

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                                                                              Big Sale! 
                                                                        This Week Only!
Were             This week      Will be
pencils  10 cents 5 cents 15 cents
pens120 cents 60 cents
79 cents
exercise books 89 cents 60 cents 85 cents
letter paper (100 pieces) 2.59 dollars 2.00 dollars 2.99 dollars
All story-books 30% off
T-shirts 4.98 dollars 3.50 dollars 6.00 dollars
jackets 22.5 dollars 18.oo dollars 25.99 dollars
1. How much did two hundred pieces of letter paper cost last week?
                                                                                                                             
2. How much will you pay for three exercise books next week?
                                                                                                                             
3. If a story-book costs 15.00 dollars. How much does it cost today?
                                                                                                                             
4. If you buy a T-shirt this week, how much more money can you save than last week?
                                                                                                                             
5. How much were two jackets last Monday?
                                                                                                                             
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