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某同学想探究二氧化锰在过氧化氢分解中作催化剂，设计了以下探究实验，请你完成实验报告和实验分析．

（1）实验报告：

实验步骤用带火星的木条检验时的现象结论
1．向试管1中倒入5mL5%的过氧化氢溶液不复燃几乎无氧气放出
2．给试管1稍微加热①②
3．向试管2中加入5mL5%的过氧化氢溶液和一匙二氧化锰③④
4．待试管2中无气泡冒出时再倒入5mL5%的过氧化氢溶液⑤⑥
5．再向试管2中加入一匙二氧化锰⑦⑧
（2）实验分析

①比较步骤1和步骤2可得出结论：过氧化氢溶液不加热几乎无氧气放出，稍加热有氧气放出．

②比较步骤1和步骤3可得出结论：______

③比较步骤4和步骤5可得出结论：______

（3）该同学觉得该实验还不完美．他还想证明MnO2在反应前后质量不变，你认为他该增加什么实验？

答案

（1）

①∵氧气能助燃，看到带火星的木条复燃，故答案为：复燃

②∵看到带火星的木条复燃，肯定有氧气放出．故答案为：有氧气放出

故答案为：③复燃；     ④有氧气放出；     ⑤复燃；    ⑥有氧气放出；⑦不复燃；⑧无氧气放出

（2）②通过实验比较，可知过氧化氢溶液常温下较稳定，故答案为：常温下过氧化氢溶液不分解．

③通过实验比较，可知MnO2的催化作用，故答案为：在MnO2的催化作用下，过氧化氢分解生成O2．

（3）MnO2可反应使过氧化氢分解出氧气，在化学反应中MnO2的性质不变，而MnO2本身不放出氧气

∴MnO2在反应前后质量不变．

完形填空
完形填空。
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