2022英语周报9年级新目标23期答案

26.(1)将红矾钠(或Cr2O-)转化为铬酸钠(或CrO-)(1分)(2)10H++2CrO-+CH3OH=2Cr3++7H2O+CO2↑(2分)(3)①锥形瓶(1分)②b(1分)③停止加热,冷却后加入沸石(2分)(4)①稀盐酸②蒸发浓缩③乙醚(各1分)(5)①偏大②88.8(各2分)解析:(1)加入40%NaOH溶液的作用是将红矾钠(或Cr2O-)转化为铬酸钠(或CrO-)(2)由反应前后的物质Na2CrO4和CrCl3可推知,甲醇的作用是还原Na2CrO4产生CrCl,所以加入CH3OH发生反应的离子方程式为10H++2CrO-+CH3OH=2r3++7H2O+CO2↑(3)①图中仪器C的名称是锥形瓶②冷凝管的冷水由a口流入、b口流出③蒸镏烧瓶加热过程中发现忘了加沸石,处理方法是停止加热,冷却后加人沸石。(4)将过滤后所得固体用稀盐酸溶解,最后将含HCI的CrCl3溶液进行蒸发浓缩、冷却结晶、过滤并用乙醚洗涤2~3次,低温干燥,即得CrCl3·6H2O晶体(5)①滴定前装有NaHY标准溶液的滴定管尖嘴部分有气泡,而滴定结束后气泡消失,则所测得的消耗标准液的体积偏大,故测得的CrCl3·6H2O的质量分数偏大

第二节书面表达One possible wersionI m Li Hua. chairman of the student Union. Impleased to know that you are coming to visit our school onDecember 15. I have been also told that you will stay withIt's a good chance to experiencel’ m writing to tellOn the moming of December 15, you will be shownaround the school. during which visitors and students fromur school can communicate with each other. talking aboutschool life and cultural differences. At noon. you are invted to have lunch in our school canteen. You can tastedumplings, moon cakes and other traditional Chinese foodOn December 16, students in our school will lead you inclimbing Huang Mountain, where you will enjoy beautifulWhat do you think of thI hewill have a nice time hereY

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