2021-2022英语周报七年级第答案

书面表达One possible versionDear PeterI'm writing to invite you to see the Chinese Painting Exhibition to be held in our city.The exhibition will start at 8: 30 am on Saturday and last till 5: 00 pm on Sunday in the city museum It'ssaid that a large number of Chinese paintings, some of which are original works by famous painters like ZhangDaqian and Qi Baishi, will be on display. Besides, there will be various souvenirs to be sold. I know you re veryinterested in traditional Chinese culture, so I can t wait to tell you the news and hope we can go together.Looking forward to your reply.You

16.(15分)(1)①agh(或hg)de(或ed)cbf(2分)②蒸馏烧瓶(1分)NO2+NH4一N2↑+2H2O(2分)平衡压强,使液体易于流下(1分)③将生成的Cl2吹出,防止VCl2被氧化(2分,合理即可)④取D中溶液少量,调pH后滴加石蕊溶液,石蕊溶液褪色(2分,合理答案也给分)(2)①滴入最后一滴标准溶液,出现砖红色沉淀,且半分钟沉淀不溶解(1分)②1:10(2分)(3)V(2分)【解析】(1)①由实验日的和原理知:A用于制备氮气,E用于于燥氮气,C中进行VCl3的分解反应,B用于防止D中水蒸气进入C而干扰实验,且E、B不能调换位置。则按气流方向,上述装置合理的连接顺序为agh(或hg)de(或ed)cbf②由图知,A中盛放NaNO2的仪器名称为蒸馏烧瓶,其中发生NaNO2与饱和NILC溶液制氮气的反应,离子方程式为NO2+NH4一N2↑+2H2O;m管可以平衡压强,使液体易于流下。③ⅤCl2容易被氧化,故实验过程中需持续通入N的作用是将生成的Cl2吹出,防止V2被氧化。④证明D中所得溶液中含有 NaClO即可证明C处有Cl2生成,则可将实验方案设计为取D中溶液少量,调pH后滴加石蕊溶液,石蕊溶液褪色。(2)①以Na2CrO4作指示剂,用AgNO3标准溶液滴定Cl-,达到滴定终点时生成砖红色沉淀Ag2CrO4,现象为滴人最后一滴标准溶液,出现砖红色沉淀,且半分钟沉淀不溶解。②由反应可得关系式:vCl2~2AgNO、VCl2~3AgNO,设VCl2、VCl3的物质的量分别为x、y,由已知数据列式得2x+3y=0.5000mol·L-1×0.046L、122g·mol-1x+157.5g·moly=1.3775g解得x=0.01mol、y=0.001mol,产品中vl3与VC2的物质的量之比为1:10(3)由右侧溶液蓝色逐渐变深推知,vO在正极上得电子转化为VO2+,则左侧电极为负极,2-失电子转化为V+,由此推断还原性V较强

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