物质溶于水时吸收或放出一定的热量,人们利用这些吸热或放热现象,制备了化学致冷袋和化学发热袋。为了增加学生的感性知识,可增加化学冰袋和暖袋的简单实用性实验。 化学冰袋 在一完好的不漏水的小塑料袋里盛放10毫升的清水,用烙铁封口(或用细线扎紧袋口),保证不漏水。另取一质量较好透明的塑料袋,称取10克干燥的硝酸铵晶体放入塑 When the substance dissolves in water, it absorbs or releases a certain amount of heat. People use these heat absorption or exothermic phenomena to prepare a chemical cooling bag and a chemical heating bag. In order to increase students’ perceptual knowledge, simple practical experiments of chemical ice packs and warm bags can be added. Chemical ice packs In an intact, water-tight plastic bag, 10 ml of clean water is placed, sealed with a soldering iron (or tied with a thin wire) to ensure no water leakage. Another good quality transparent plastic bag is used. Weigh 10g of dried ammonium nitrate crystals into plastic.