问题 填空题

为区别NaOH和Na2CO3两种无色溶液,某同学设计了以下两种实验方案:

方案1:分别取少许两种溶液,各滴入几滴无色酚酞试液,根据酚酞试液是否变红色判断各是哪种溶液?

方案2:分别取少许两种溶液,各加入少量澄清石灰水,根据是否有白色沉淀生成判断各是哪种溶液?

请回答:

(1)该同学设计的两个方案有一个是正确的,该方案是______;另一个方案是不正确的,原因是______.

(2)请你再设计一个实验,区别上述两种溶液:

实验操作实验现象实验结论和化学反应方程式
   

答案

(1)由于碳酸钠显碱性也能够使酚酞试液变红,所以方案1错误;加入少量澄清石灰水,根据是否有白色沉淀生成,由于氢氧化钠与氢氧化钙不反应,所以产生沉淀的是碳酸钠.

(2)滴加盐酸有气泡说明含有碳酸根离子即是碳酸钠,如果滴加氯化钙有白色沉淀生成,说明是碳酸钠;

故答案为:(1)方案2;碳酸钠也显碱性;

(2)

实验操作实验现象实验结论和化学反应方程式
取两只试管各取少量待测液,分别滴加稀盐酸有气泡生成有气泡生成的是碳酸钠,无现象的是氢氧化钠

NaOH+HCl=NaCl+H2O

Na2CO3+2HCl=2NaCl+H2O+CO2

问答题 简答题
阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项,选项中有两项为多余选项

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