问题 问答题

实验室利用如图所示装置进行NaHCO3的受热分解实验.请回答:

(1)加热一段时间后,烧杯中观察到的实验现象是______.

(2)实验结束时的正确操作是______;理由是______.

(3)NaHCO3受热分解的化学方程式:______.

(4)33.6gNaHCO3受热分解放出气体在标况下的体积______.

答案

(1)NaHCO3不稳定,加热分解生成的CO2会使澄清石灰水变浑浊,生成碳酸钙沉淀,故答案为:澄清石灰水变浑浊;

(2)如先撤酒精灯,温度降低,试管内压强减小,会导致倒吸而使试管炸裂,应先将导管从溶液中移出,再熄灭酒精灯,

故答案为:先将导管从溶液中移出,再熄灭酒精灯;反过来操作会引起倒吸;

(3)NaHCO3不稳定,加热分解生成的CO2、H2O和Na2CO3,反应的方程式为2NaHCO3

  △  
.
 
Na2CO3+CO2↑+H2O,

故答案为:2NaHCO3

  △  
.
 
Na2CO3+CO2↑+H2O;

(4)n(NaHCO3)=

33.6g
84g/mol
=0.4mol,则生成n(CO2)=0.2mol,V(CO2)=0.2mol×22.4L/mol=4.48L,

故答案为:4.48L.

阅读理解

C

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