题干

某同学在实验室通过实验对草酸进行如下研究。

【查阅资料】①无水硫酸铜吸水后由白色变为蓝色

②氯化钯(PdCl2)溶液遇CO产生黑色沉淀

【实验准备】选用下列实验装置(气密性良好,部分固定装置已略去):

  

【实验探究】检验草酸分解的产物。

实验步骤

实验现象

实验结论及分析

⑴按A→D→B→C连接仪器

⑵关闭K,点燃A处酒精灯

D中____B中澄清石灰水变浑浊C中产生黑色沉淀,气球鼓起

草酸分解生成了CO2、CO和H2O

B中反应的化学方程式是:____

②C中气球的作用是____

上一题 下一题 0.0难度 选择题 更新时间:2019-12-12 11:05:17

答案(点此获取答案解析)

白色固体变成蓝色,Ca(OH)2 + CO2= CaCO3↓+ H2O,收集尾气(或尾气处理装置)

同类题5

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    You dash through a crowded railway station, tripping over bags, spilling (泼出) your coffee, only to have the doors slide shut in your face, leaving you breathless on the platform as the train pulls away,

    But at least, if you're in France, someone may be playing the piano for you. But it won't be performed by a paid musician, or even a street entertainer playing for coins. It will just be a random passer - by, jamming for the fun of it on one of the pianos that the national railroad company, S. N. C. F., has fixed in nearly 100 stations across France. They are free for anyone to play, and travelers from all walks of life have taken to doing just that.

    Gares & Connexions, the S. N. C. F. division that manages its stations, rents the instruments from the producer, Yamaha: which maintains them and tunes them every month or two. The first one was set up in the Gare Montparnasse in Paris in 2012.

    The music, mixed with the sounds of shouting passengers, screaming trains and rolling suitcases, gives French stations a special soundscape. The amateur musicians have included Irish soccer fans and even babies. In 2014, Gares & Connexions and Yamaha organized a nationwide contest called Your Turn to Play, asking participants to submit videos of themselves using one of the pianos. It drew nearly 900 entries.

    Isn't the railroad company taking a big chance? Apparently not: “None of the instruments has been vandalized to this day, or even merely damaged,” said Claire Foumon, a spokeswoman for Gares & Connexions. “They are shared and respected by all.”

    So if you miss a train in Paris; Bordeaux or Marseille one day, perhaps someone will be playing a favorite piece that will ease your pain. Or perhaps you'll sit down and play your annoyance away yourself.