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，污水碳酸鈉可與水結合形成結晶水合物并放熱。 文字測試中的水量由橡膠控制。 它不應太大，也不應太小。 在該試驗中，水合釋放的熱量不多，并且試管壁的值相對較小。 稠，所以不容易干燥。 該實驗在自封袋中具有明顯的優(yōu)勢。 從拉鏈袋的外部輕輕擦手，以感知溫度的變化。 可以感覺到，在大量碳酸鈉中加水顯然是放熱的。

　　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.

　　當探索銨鹽與堿之間形成氨氣的反應性質時，可以將Ca（OH）2和NH4Cl晶體添加到自封袋中，密封袋口，然后用手從袋子上輕輕揉搓 自封袋的外部，以觀察袋的內(nèi)部。 如果有氣體，還可以張小嘴聞到氣體。 如果要使現(xiàn)象更明顯，也可以將自封袋放入熱水中加熱浴缸。

　　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.