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进入9年级学习化学,我们亲身体验了一系列的探究实验,感受到了化学的无穷魅力。覃浪在回顾整理下列实验中提炼了许多探究方法。
实验一、探究二氧化碳与水的反应(取四朵用紫色石蕊溶液染成紫色的干燥的小花,进行下图所示实验)
实验现象:(I)、(IV)中的小花变红。
设计(Ⅱ)、(Ⅲ)实验的目的是: 43 。
该实验的探究方法是:设计分析 44 (填“A”或“B”或“C”,获得结论。
A.仅一个单因素的实验
B.有多种因素的对比实验
C.用前面实验的生成物继续实验
实验二、验证二氧化碳与氢氧化钠溶液也发生了反应
我们知道,二氧化碳能使澄清石灰水发生反应生成碳酸钙而变浑浊。彩云同学查阅资料发现:氢氧化钠与氢氧化钙化学性质十分相似,也能与二氧化碳发生反应,但此反应无明显实验现象,其反应的化学方程式为: 45 。她为了能证明氢氧化钠与二氧化碳在溶液中确实发生了反应,设计了如下方案。请你将她设计的方案补充完整:
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| 实验步骤和方法 | 实验现象 | 实验结论 | 启示 |
| 方案1 | 向一个软塑料瓶中充满二氧化碳,再注入少量氢氧化钠溶液,盖紧瓶盖,摇动塑料瓶。 | 46 | 47 | 从反应物二氧化碳的减少(压强减小)来判断反应的发生 |
| 方案2 | 48 | 49 | 50 | 从生成物的存在来判断反应的发生 |
官龙同学认为彩云同学设计的方案1中,不能得出CO2与氢氧化钠是否确实发生了反应,理由是什么? 51 。
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进入9年级学习化学,我们亲身体验了一系列的探究实验,感受到了化学的无穷魅力。覃浪在回顾整理下列实验中提炼了许多探究方法。
实验一、探究二氧化碳与水的反应(取四朵用紫色石蕊溶液染成紫色的干燥的小花,进行下图所示实验)
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实验现象:(I)、(IV)中的小花变红。
设计(Ⅱ)、(Ⅲ)实验的目的是: 43 。
该实验的探究方法是:设计分析 44 (填“A”或“B”或“C”,获得结论。
A.仅一个单因素的实验 B.有多种因素的对比实验
C.用前面实验的生成物继续实验
实验二、验证二氧化碳与氢氧化钠溶液也发生了反应
我们知道,二氧化碳能使澄清石灰水发生反应生成碳酸钙而变浑浊。彩云同学查阅资料发现:氢氧化钠与氢氧化钙化学性质十分相似,也能与二氧化碳发生反应,但此反应无明显实验现象,其反应的化学方程式为: 45 。她为了能证明氢氧化钠与二氧化碳在溶液中确实发生了反应,设计了如下方案。请你将她设计的方案补充完整:
|
| 实验步骤和方法 | 实验现象 | 实验结论 | 启示 |
| 方案1 | 向一个软塑料瓶中充满二氧化碳,再注入少量氢氧化钠溶液,盖紧瓶盖,摇动塑料瓶。 | 46 | 47 | 从反应物二氧化碳的减少(压强减小)来判断反应的发生 |
| 方案2 | 48 | 49 | 50 | 从生成物的存在来判断反应的发生 |
官龙同学认为彩云同学设计的方案1中,不能得出CO2与氢氧化钠是否确实发生了反应,理由是什么? 51 。
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(12分)如图是空气中氧气含量的测定装置。试回答:
![]()
(1)盛在仪器A中的物质常用红磷,反应的现象是 (46) 。 该该反应的文字表达式和化学式为 (47)
(2)该实验得到的结论是(48) 。
(3)实验中,测得氧气的体积分数偏小的原因可能有(至少回答2
条) (49) 、 (50) 。
(4)如果把A中的红磷换成木炭,请问如何改进这个实验使之成功呢?
| 改进方案 | 改进原理 |
| (51) | (52) |
木炭燃烧反应的文字表达式和化学式为 (53)
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Usually, there is a teacher-parent meeting in every school year. Some students enjoy it, some don’t. Tom, a little boy invited his mother to attend his school's first teacher-parent meeting. To the little boy's __36__, she said she would go. This __37__ be the first time that his classmates and teacher __38__ his mother and he felt __39__ of her appearance. Although she was a beautiful woman, there was a severe scar (疤痕) that 40 nearly the entire right side of her face. The boy never wanted to _41__ why or how she got the scar.
At the meeting, the people were __42__ by the kindness and natural beauty of his mother __43__ the scar, but the little boy was still embarrassed and 44 himself from everyone. He did, however, get within __45__of a conversation between his mother and his teacher.
The teacher asked __46__, "How did you get the scar on your face?"
The mother replied, "__47__ my son was a baby, he was in a room that caught fire. Everyone was __48__ afraid to go in because the fire was __49__,so I went in. As I was running toward his bed, I saw a long piece of wood coming down and I placed myself over him trying to protect him. I was knocked __50__ but fortunately, a fireman came in and saved both of us." She __51__ the burned side of her face. "This scar will be __52__, but to this day, I have never __53__ what I did."
At this point, the little boy came out running toward his mother with tears in his eyes. He held her in his arms and felt a great __54__ of the sacrifice (牺牲) that his mother had made for him. He held her hand 55 for the rest of the day.
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