问题 实验题

(10分)某化学兴趣小组拟用右图装置对某粗锌样品进行纯度检测。请填写以下实验报告。

(1)实验目的:                                    

(2)实验步骤:

①称取10.0 g粗锌置于铜网中,按图示装置组装后,称得仪器和药品总质量为120.0 g。

②将铜网插入足量的稀盐酸中,有关反应的化学方程式为                        

③反应完全后,称得装置总质量为119.8 g,则粗锌的纯度为        

(3)问题探究:(已知碱石灰为.Na()H和CaO的混合物)

①该实验中碱石灰的作用是        ;若不用碱石灰,则所测得的粗锌纯度将        ;(填“偏大”、“偏小”或“无影响”)。

②若将粗锌换成石灰石,原实验方案        (填“能”或“不能”)用于石灰石样品纯度的测定,理由是                                。

答案

(1)测定粗锌样品中锌的质量分数(或纯度)(2分)

(2)②Zn+2HCl=ZnCl2+H2↑(2分)       ③65%(2分)

(3)①吸收水蒸气、氯化氢气体(1分)      偏大(1分)  

②不能(1分)  碱石灰能吸收反应生成的CO2(1分)

(1)由于是对某粗锌样品进行纯度检测,所以实验目的是测定粗锌样品中锌的质量分数(或纯度)。

(2)②锌是活泼的金属,和盐酸反应生成氢气,方程式为Zn+2HCl=ZnCl2+H2↑。

②减少随质量就是产生的氢气,则氢气是0.2g,所以消耗锌是6.5g,所以粗锌的纯度为6.5g÷10.0g×100%=65%。

(3)①由于产生的氢气中含有水蒸气和氯化氢,所以碱石灰的作用是吸收水蒸气、氯化氢气体。如果没有碱石灰,则产生的氢气偏多,测定结果偏大。

②碳酸钙和盐酸反应生成的CO2,能被碱石灰吸收,所以不能。

完形填空
完形填空。
     Alfred Nobel became a millionaire and changed the ways of mining,construction, and warfare as
the inventor of dynamite (炸药). On April 12, 1888, Alfred's brother Ludwig died of heart attack. A
major French newspaper   1   his brother for him and carried an article   2   the death of Alfred Nobel.
"The merchant of death is dead."the article read." Dr. Alfred Nobel, who became   3   by finding ways
to kill more people faster than ever before,died yesterday. "Nobel was   4   to find out not that he had
died, but that, when his time was up, he would be thought of only as one who profited from   5   and
destruction."
     To make sure that he was   6   with love and respect. Nobel arranged in his   7   to give the largest
part of his money to   8   the Nobel prizes,which would be awarded to people who made great   9   to
the causes of peace, literature, and the sciences. So  10 , Nobel had to die before he realized what his
life was really about.
( )1. A. found    
( )2. A. introducing
( )3. A. famous    
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( )5. A. death    
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( )10. A. generally 
B. misunderstood 
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D. advertising  
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D. attack       
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单项选择题