Self sealing bag refers to a bag that does not need to be sealed automatically with any tool. The common types are zipper type and self-adhesive type. In this case, the zipper type self sealing bag has the advantages of low price, good transparency and airtight. The zipper is suitable for simple operation and convenient operation. It enables students to better "touch" drugs and bring more sensory stimulation. Recently, it is more and more popular among chemistry teachers. Since it is convenient to carry out the reaction between liquid and liquid in the test tube, it is not beneficial to use the test tube if there is solid participation in the reaction. If the heat requirement of the reaction is not too high (heating is not required), please consider exploring in the self sealing bag.

　　例如，污水碳酸钠可与水结合形成结晶水合物并放热。 文字测试中的水量由橡胶控制。 它不应太大，也不应太小。 在该试验中，水合释放的热量不多，并且试管壁的值相对较小。 稠，所以不容易干燥。 该实验在自封袋中具有明显的优势。 从拉链袋的外部轻轻擦手，以感知温度的变化。 可以感觉到，在大量碳酸钠中加水显然是放热的。

　　For example, sodium carbonate in sewage can combine with water to form crystalline hydrate and release heat. The amount of water in the text test is controlled by rubber. It should not be too big or too small. In this experiment, the heat released by hydration is not much, and the value of tube wall is relatively small. It's thick, so it's not easy to dry. This experiment has obvious advantages in self sealing bags. Gently wipe your hands from the outside of the zip pocket to sense the temperature change. It can be felt that adding water to a large amount of sodium carbonate is obviously exothermic.

　　当探索铵盐与碱之间形成氨气的反应性质时，可以将Ca（OH）2和NH4Cl晶体添加到自封袋中，密封袋口，然后用手从袋子上轻轻揉搓 自封袋的外部，以观察袋的内部。 如果有气体，还可以张小嘴闻到气体。 如果要使现象更明显，也可以将自封袋放入热水中加热浴缸。

　　When exploring the reaction properties of ammonia formed between ammonium salt and alkali, Ca (OH) 2 and NH4Cl crystals can be added to the self sealing bag to seal the opening of the bag, and then gently rub the outside of the self sealing bag from the bag by hand to observe the inside of the bag. If there is gas, you can open your mouth and smell it quickly. If you want to make the phenomenon more obvious, you can also put the self sealing bag into the hot water to heat the bathtub.