2022英语周报高一外研第43期答案

15.(1)三颈烧瓶(1分);温水浴(或水浴加热,1分)(2)将PbO还原为Pb2+(1分);PbO2+2H++H2O=Pb2++2H2O+O↑(2分);PbO+2H=Pb2+H20(2分)(3)加热样品使其分解,将产生的气体通过装有无水硫酸铜的干燥管(2分);无水硫酸铜不变蓝色(1分)(4)70%(2分);偏低(2分)【解析】本题主要考查以废旧铅酸电池中的铅膏为原料制备草酸铅的工艺流程,考查学生对元素化合物的理解能力和综合运用能力。(1)仪器ⅹ的名称为三颈烧瓶;根据“脱硫”时适宜温度为35℃,所以采用温水浴加热2)PbO具有强氧化性,能够将双氧水氧化,加双氧水的目的是将PbO还原为Pb2+,反应的离子方程式为PbO2+2H++H2O—Pb2++2H2()+O)↑;根据已知信息②可知PhO溶解的离子方程式为Pb+2H+Pb2++H2((3)二者受热都易分解生成P以,根据元素守恒可知,碱式碳酸铅分解可以生成水,利用无水硫酸铜不变蓝色,证明样品中没有碱式碳酸铅(4)根据Pb2++H2YPbY-+2I+,消耗EDTA标准溶液28.00m,则n(PbC2O1)=n(Pb2+)=n(H2Y2)=0.038L×0.05m0l·L-1,则250m溶液中n(PCO)=0.028L×0.05m0l,L-1×250,因2500.028×0.05×25×295此草酸铅的纯度100%=70%;若滴定完成时发现滴定管内有气泡,则滴定过程中实际消耗的DTA标准液体积大于滴定管测得的体积,导致测定结果偏低。

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