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NO_2被水吸收生成HNO_3和NO,以及NO被氧化生成NO_2,是高中化学的重要反应。教学中,若设置下述实验,会给学生以鲜明、深刻的印象,取得更好的教学效果。 [实验步骤] 1.铜片跟浓硝酸反应,用干燥的大试管收集产生的二氧化氮。当整个试管呈现深红棕色时,迅速用软木塞将管口塞住。 2.将充满二氧化氮的大试管倒立于水槽中,并固定在铁架台上。将管口的塞子拔出,可立刻看到试管内液面逐渐上升,红棕色消失。液面约上升至管长的2/3处停止,管内尚有约1/3的空间(NO)。 3.将事先收集满氧气的20毫升注射器的针头
NO 2 is absorbed by water to generate HNO 3 and NO, and NO is oxidized to produce NO 2 , which is an important reaction in high school chemistry. In the teaching, if the following experiment is set up, students will have a vivid and profound impression and achieve better teaching results. [Experimental Procedure] 1. The copper tablets react with concentrated nitric acid, and the produced nitrogen dioxide is collected in a large dry tube. When the entire tube appeared dark reddish brown, the tube was quickly plugged with a cork stopper. 2. Invert the large tube full of nitrogen dioxide in the sink and fix it on the iron stand. Pulling out the stopper of the nozzle, you can immediately see the liquid level in the tube rise gradually, red and brown disappear. The liquid level rose to about 2/3 of the pipe length, and there was about 1/3 of the space (NO) in the pipe. 3. The needle of a 20 ml syringe that will be collected in advance of full oxygen