2022英语周报3559期答案

17.(1)甲(1分)H2C2O4·2H2O=3H2O+CO↑十CO2↑(1分)冷凝草酸蒸气,避免对二氧化碳的检验产生于扰(1分)C0有毒,缺少尾气处理装置(1分)(2)HCO:+ H;C: O. HC2 O*+CO:1+H:O(1分)(3)反应产生的锰离子起催化作用,加快了反应速率(1分)5H2C2O4+2MnO4+6H=10CO2↑2Mn2++8H2O(1分)(4)使受热均匀,便于控制温度(1分)(5)烧杯、玻璃棒、100mL容量瓶、胶头滴管(1分)当滴入最后一滴酸性高锰酸钾溶液时,溶液由无色变到粉红色(或淡红色),且半分钟内颜色不变(1分)12.6aV8m100%(1分)【解析】(1)加热固体,应避免试管炸裂,如固体易熔化,应避免药品熔化后流出试管,选装置甲;草酸不稳定,受热易分解,且草酸易升华,所以分解产物中含有草酸,草酸常温下为无色晶体,所以装置B的作用是冷却草酸蒸气,装置C用来检验二氧化碳,装置D中有碱性溶液,能吸收二氧化碳,装置E是检验二氧化碳是否除尽,装置F用来干燥气体,如果装置G中固体变红色、装置H溶液变浑浊,说明生成气体中含有CO,CO有毒,不能直接排放到空气中,所以应该有尾气处理装置。(2)草酸的酸性强于碳酸,且草酸足量,离子方程式为HCOz+H2C2O4—HC2O-+CO2↑+H2O(3)由题意可知,生成的锰离子能作催化剂,能加快反应速率,该反应的离子方程式为2MnO7+5H2C2O4+6H—2Mn2++10CO2↑+8H2O(4)该实验要求温度为55~60℃,故采用水浴加热法,水浴加热的优点为使受热均匀,便于控制温度(5)配制100mL草酸溶液,需要称量、溶解、转移、洗涤、定容等操作,则需要的玻璃仪器有烧杯、玻璃棒、100mL容量瓶、胶头滴管;采用0.1mol·L-酸性高锰酸钾溶液滴定该草酸溶液,滴定终点吋,溶液会呈现高锰酸钾溶液的颜色,因此滴定终点的现象是当滴入最后一滴高锰酸钾溶液时,溶液由无色变到粉红色(或淡红色)且半分钟内颜色不变;由化学方程式可知,参加反应的草酸的物质的量为2.5aV×10-mol,则100ml溶液中含草酸的物质的量=25V×10-3mol100mL=12.5aV×10-3mol.则所得草酸晶体的纯度为20 mI125xV×103mol×126g·ml-100%=126VIn g×100%。

Li HI第二节The next day when i arrived at school. I didn't findAlice. I felt everything was very dark. I had a bad feelingwhen I was looking for her. I found some guys werebothering Alice, and this time they were hitting her andpulling her hair. I heard one of the guys say, "You have togive me all your homework, or we'll keep on hitting youI did not know what to do. I was very worried, so mydecision was to call the policeWhen the police arrived, the guys who were bullyingAlice were caught. We all had to go to the school office. Iwas in the office as a witness. Alice was a victim, andhose who bullied her were guilty. When my parentsarrived, theyfelt piroud of me. Alice told her parenteverything. She was extremely grateful and kept thankingme. From that day on, I got a best friend for life, andAlice learned how to defend herself

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