1. Weighing: Weigh a certain amount of crude salt, add it into water and dissolve it for subsequent separation and purification operations. Specific weighing contents: Weigh about 4g of raw salt, add it into a beaker containing about 12mL of water, and stir while adding it until the raw salt is no longer dissolved. The purpose of this step is to completely dissolve the crude salt for subsequent separation and purification operations.
2. Filtering: After folding the filter paper, dip the glass rod in water to make it close to the inner wall of the funnel and make the upper edge of the filter paper lower than the funnel mouth, and the liquid level of the solution is lower than the upper edge of the filter paper. The mouth of the beaker for pouring liquid should be close to the glass rod, one end of the glass rod is close to the side with three layers of filter paper, and one end of the funnel is close to the inner wall of the beaker for holding filtrate.
3. Evaporation: The purification and evaporation of salt means that the solution after the original salt is dissolved is put into an evaporating dish, heated with fire and constantly stirred, so that the water evaporates to a certain extent, and then taken out and dried to obtain salt crystals with high purity. Pay attention to heating and stirring when evaporating to avoid burning or caking.
4. Drying: using the waste heat of the evaporating dish to evaporate the filtrate, and heating to evaporate the water in the original salt to obtain salt crystals with high purity. In the drying process, attention should be paid to temperature and time to avoid salt crystallization and deterioration caused by excessive heating.
Related knowledge of crude salt purification experiment
1, the experimental results show that there are a lot of impurities in the solution after the original salt is dissolved in water. This is because the minerals and impurities in the original salt can not be completely separated when dissolved, resulting in a large number of ions in the solution. By heating evaporation, the water in the solution can be evaporated, leaving salt crystals. During evaporation, attention should be paid to heating and stirring to avoid burning or caking.
2. The experimental results show that crystallization is one of the key steps in the purification of crude salt. In the process of crystallization, salt crystals can be gradually precipitated by controlling temperature and time. However, if the crystallization time is too long or the temperature is too low, it may lead to the deterioration of salt crystals and affect the purification effect. Therefore, we must pay close attention to the changes of temperature and time in the crystallization process to ensure the quality and purity of salt crystals.
3. Drying is the last step of purifying crude salt. Water and other volatile impurities in salt crystals can be removed by air drying. In the drying process, attention should be paid to temperature and time to avoid salt crystallization and deterioration caused by excessive heating. At the same time, it is necessary to test the quality of dried salt crystals to ensure that their purity and color meet the requirements.