题干

同学们来到化学实验室,意外看到了一个不和谐的“音符”(如下图)。由此,激发了同学们的探究欲望。

(1)同学们取该瓶中少量溶液 滴加稀盐酸,看到冒气泡,说明药品已变质,变质反应的化学方程式为:____。
【进行猜想】小天的猜想:NaOH 溶液部分变质;
你的猜想:____。
【实验探究】小天设计如下实验来验证自己的猜想,请完成下表:
探究目的探究步骤预计现象
除尽溶液中的CO32-①:取少量溶液于试管中,滴加足量的CaCl2试剂____ 
证明溶液中尚存NaOH ②:向实验①过滤后所得溶液中滴加酚酞试液 
____
假设你的猜想正确,并按小天的实验方案进行实验,则你观察的现象____。
【实验反思】(1)下列物质1.BaCl 2溶液 2.Ca(NO3)2溶液 3.Ca(OH)2溶液4.Ba(OH)2溶液, 不能替代小天实验中CaCl 2溶液的是____(填序号) 。
(2)小天第二次滴加的试剂除用指示剂外,还可以用____替代。
【拓展应用】保存NaOH 溶液的方法是____ 。
上一题 下一题 0.0难度 选择题 更新时间:2016-05-30 10:00:27

答案(点此获取答案解析)

2NaOH + CO2=Na2CO3+ H2O,NaOH \u6eb6\u6db2\u5168\u90e8\u53d8\u8d28,\u51fa\u73b0\u767d\

同类题3

完形填空

    The four famous rock stars were due to arrive at any moment and a large crowd of young people had gathered at the airport to welcome them.The police found it difficult to keep the crowd under1after the plane landed and the performers appeared.They smiled and waved2at everybody.Dressed in pink shirts and light blue trousers,and with their long hair and their musical instruments3their shoulders,the four young men looked very much4.

    In spite of the large number of policemen5,it was clear that the group would not be able to get to their waiting car6.Word had got out that they had written a new song which would be7when they performed at the grand hall that evening.They were now8with crying of “Play something! Play your new song!”

    Even the police looked9when the young men unfolded their instruments and prepared to do one of their numbers as the10for getting out of the airport.The crowd settled down and listened to the first11of the new song. As soon as it was over,there was a great burst of applause and then everyone started12and shouting like crazy. Several young women fainted and had to be carried away by the13unit which was standing by.Greedy for more, the crowd14a repeat performance.Once again the performers gave in,but when the crowd requested still another song,the group cheerfully but firmly15.

    Now closely surrounded by the police,they put away their16and stared towards their car which was some distance away.The crowd pushed forward,but the policemen,17arm in arm,prevented anyone from getting through. It took the singers a long time to reach their18.Finally,however,they got in and were just about to drive away when a young woman,who had19to get past the police,jumped onto the roof of the car.She shouted loudly as two policemen20her away and the car began moving slowly through the cheering crowd.