2022英语周报新目标八下3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

23.(16分)(1)AgCI(2分)(2)aGcL+S2Ag2S+2C-(2分)Ag2S比AgC的溶解度小(2分)(3)①SO:(2分)②S(2分)(4)①O2(1分)②Ag2S的悬浊液(1分)③102、4NaCl、2S(2分)④O2将Ag2S氧化生成S时有Ag+游离出来,NaCl中大量的C与游离的Ag+结合成AgC沉淀,由于c(Ag+)减小,有利于③中反应平衡正向移动,B中最终出现乳白色沉淀(2分).【解析】(1)I中NaCl与AgNO3溶液混合发生反应Ag++C-AgCl↓,故白色沉淀是AgCl(2)向所得固液混合物中加入Na2S溶液,S2与Ag+生成Ag2S,使平衡AgCl(s)Ag+(aq)+Cl(aq)正向移动,最终白色沉淀变黑,该反应的离子方程式为2AgC+s2-Ag2S+2Cl-。沉淀转化的主要原因是Ag2S比AgC!的溶解度小。(3)①向X中滴加Ba(NO)2溶液产生白色沉淀,说明X中含有SO。②向Y中滴加K溶液,产生黄色沉淀说明白色沉淀Y为AgCl;可进一步确定乳白色沉淀中含有AgC1和单质S(4)①在MnO2作催化剂的条件下,H2O2发生分解反生成O2,即A中产生的气体是Q2②C中盛放的物质W是Ag2S的悬浊液③B中产生沉淀的反应为2Ag2S+O2+4NaCl+2H2O、4AgCl+2S4NaOH④O2将Ag2S氧化生成S时,有Ag+游离出来,NaC中大量的C-与游离的Ag+结合成AgC!沉淀。由于c(Ag+)减小,有利于③中反应平衡正向移动B中最终出现乳白色沉淀。

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