推荐回答(2个)
对比以下两题:
1、除去氯化钠溶液中少量盐酸,没有指示剂条件下可用( )
A 碳酸钙粉末
B 氧化钙粉末
C 氢氧化钙粉末
因为只有A能与盐酸反应生成气体,且不溶于水,过量也没有关系,可以过滤除去的,不生成气体了,就没有盐酸了。
其它两种过量时会增加新的杂质
2、某电镀厂排出的污水,其pH<7,并含有硫酸铜,要除去有毒的硫酸铜,同时调节pH至中性,可选用下列物质中的( )
A生石灰 B碳酸钙
是PH<7,显酸性,要除去硫酸铜,只能与碱反应了,生石灰与水反应生成氢氧化钙,再与硫酸铜反应生成氢氧化铜。
碳酸钙只中和,不会与硫酸铜反应
为什么两题都选A?解释一下为什么其他得不能选
3、某溶液甲由3种物质混合而成,溶液呈碱性
(1)取样,加入足量稀盐酸,无明显现象
(2)取样,加入适量氯化镁,产生白色沉淀和另一种无色溶液乙
(3)向溶液乙中加入氯化钡溶液,得到不溶于稀硝酸的白色沉淀和无色溶液丙
(4)将溶液丙置于蒸发皿中加热,蒸干只得到氯化钠固体
溶液甲哪3种物质组成?
氢氧化钠,硫酸钠,氯化钠
4、什么是电镀溶液
高中后才学到的,镀铜时,常用硫酸铜作电镀液,导电作用,提供待镀金属离子的
第一题
选A 应该是因为CaCO3+HCl生成的是气体和水..气体可以跑掉的..而且不会引入新的杂质..
第二题
首先硫酸铜是不跟碳酸钙反应的..因为不生成沉淀 气体 或 水 这个反应是不进行的.. 选A是因为CaO在水中可以堪称Ca(OH)2 与硫酸铜反应生成氢氧化铜沉淀..可以过滤除去的... 并且氢氧化钙是碱..可以雨生成的硫酸也反应掉...最终PH就是7了..
3、某溶液甲由3种物质混合而成,溶液呈碱性
(1)取样,加入足量稀盐酸,无明显现象
(2)取样,加入适量氯化镁,产生白色沉淀和另一种无色溶液乙
MgCl2+这样东西生成氢氧化镁白色沉淀和一种氯盐的溶液 有OH根存在
(3)向溶液乙中加入氯化钡溶液,得到不溶于稀硝酸的白色沉淀和无色溶液丙
BaCl2所对应的沉淀就是BaSO4或者BaCO3 因为不溶于稀硝酸 所以不是BaCO3
所以沉淀 必定是BaSO4 有硫酸根存在
(4)将溶液丙置于蒸发皿中加热,蒸干只得到氯化钠固体
由此可知溶液丙和溶液乙分别含有氯化钠和硫酸钠
有上面的推论可知
三种物质是氢氧化钠 硫酸钠 氯化钠
(这个是我自己做出来的..不知道对不对..)
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