题干

某化学课堂上同学们正在进行酸、碱、盐知识的探究,以下是教学片断,请你参与其中并认真填写空格.

【学生实验】将二氧化碳分别通入澄清石灰水和氢氧化钠溶液中,观察到前者变浑浊,后者无明显现象.
【学生板演】澄清石灰水变浑浊的原理____(用化学方程式表示)
【提出问题】二氧化碳通入氢氧化钠溶液中无明显现象,两者是否发生了化学反应?
【猜想假设】猜想①:两者发生了化学反应;猜想②:两者没有发生化学反应
【实验探究】
(1)小华设计了如图所示的A、B两个实验.
实验现象:A中软塑料瓶変瘪,B中____
(2)小红认为小华的实验是可行的,其共同原理是二氧化碳和氢氧化钠溶液反应,使容器内压强降低.小明同学却对此提出质疑,他认为小华的实验不严谨,其理由是____,要得到科学严谨的结论,仍利用该装置,补做的对比实验是____
(3)小宁设计的是通过检验生成物来验证猜想,请帮她填写实验报告.

 实验步骤 实验现象 实验结论
 向B实验后的溶液中加入
____
 
____
 验证了二氧化碳和氢氧化钠溶液反应

【实验结论】二氧化碳和氢氧化钠溶液发生了反应.
【反思拓展】通过此探究实验,我们发现,对于没有明显现象的化学反应,可以从两个不同的角度证明反应的发生,这两个角度是________

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答案(点此获取答案解析)

CO2+Ca\uff08OH\uff092\u2550CaCO3\u2193+H2O,\u6c14\u7403\u81a8\u80c0\u53d8\u5927,\u4e8

同类题5

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    Winters are long and unforgiving in North Dakota. The winter of 1996 was especially brutal. It was a hard time in my own life too, A neck injury had kept me flat in bed for nearly a year. “Just in time for Easter,” my husband, Dick, said. But how could I feel the joy when the snow was four feet deep and I had months of painful physical treatment ahead?

    I was doing the dishes one day, feeling hopeless when there was a tap against the glass. It was a branch of the troublesome cottonwood (棉白杨).Back in the fall of 1979, it was a new subdivision (分支) then, an eight-foot stick. The people who'd briefly occupied the house before us had placed the pipe from the pump next to it. The earth was so wet that the poor thing had fallen down, most of its bare root system pointing skyward, and blowing hopelessly back and forth in the cold wind. Dick decided to pull it out one day, but I disapproved of it.

    “Look at how hard it's trying!” I said, pointing to the way it strongly kept hold of the earth. “It deserves a chance.”

    Dick borrowed some tools. We packed dry soil around the tree and put up some stakes (桩) into the ground, making it stand upright. That winter was still terrible. Surprisingly, in the spring my “rescue stick” put forth a few leaves, then with lots of branches. The year after that, we were able to remove the stakes. By the 1990s that little stick was a giant, towering over the house.

    Now the tapping at the window continued, louder as the wind picked up, almost as though to tell me to look up. At last, I did. I caught ray breath. In the window against the icy blue sky, thousands and thousands of fresh red buds were waving in the wind.

    The tree was bursting with life and I had a wonderful Easter.