Experiment Dissolution and filtration of coarse salt purification with detailed steps and precaution

Coarse salt purification. 1. Experimental procedure: dissolution, filtration, evaporation.

Second, the role of the glass rod:

1) Stir when dissolving to speed up dissolution.

2) Drain when filtering.

3) When evaporating, stir to make the heating even.

Third, the key points to note in filtration: one stick, two low, three leaning.

Fourth, the key points in evaporation: stirring the glass rod and evaporating the filtrate with waste heat.

Take a small amount of coarse salt and put it into a beaker, add an appropriate amount of water, stir with a glass rod, after the coarse salt is fully dissolved, pour the turbid salt water into the installed filter along the glass rod, and then heat the obtained filtrate in the evaporation dish until a large amount of solids appear in the filtrate, stop heating.

The main ingredient of table salt is NaCl, coarse salt refers to NaCl containing impurities, soluble impurities are mostly magnesium chloride, calcium chloride, etc., and insoluble sediment. The main operation of coarse salt purification can be divided into two parts: one is filtration, the purpose is to separate the insoluble solid impurities from NaCl, and the other is crystallization, the purpose is to separate the NaCl from the soluble impurities with a steep solubility.

The purpose of weighing coarse salt and purified salt before and after the experiment is to calculate the yield of coarse salt. When making the filter device, pay attention to three key points: 1. The edge of the filter paper is lower than the edge of the funnel, 2. The tip of the funnel is close to the inner wall of the beaker, 3. Drain with a glass rod and stick it to the three layers of filter paper.

In the process of evaporating the filtrate, stirring with a glass rod is to prevent the liquid from splashing due to the high local temperature of the solution.

Coarse salt purification. 1. Experimental procedure: dissolution, filtration, evaporation.

Second, the role of the glass rod:

1) Stir when dissolving to speed up dissolution.

2) Drain when filtering.

3) When evaporating, stir to make the heating even.

Third, the key points to note in the filtering: one disadvantage of the land defense sticker, two low, three dependent.

Fourth, the key points in evaporation: stirring the glass rod and evaporating the filtrate with waste heat.

Take a small amount of coarse salt and put it in a beaker.

Medium, add an appropriate amount of water, stir with a glass rod, wait for the coarse salt to be fully dissolved, pour the turbid salt water along the glass rod into the installed filter, and then put the obtained filtrate in the evaporation dish.

Medium heating until a large amount of solids appears in the filtrate, and the heating is stopped.

The purity is small: the amount of water poured is insufficient when dissolved, and the sodium chloride is only partially dissolved; Liquid spills when dissolved; Failure to drain with glass rods during filtration leads to liquid spillage; When filtering, the beaker is removed without waiting for all the filtrate to flow into the beaker; Heating stops when evaporation dries; When evaporating, the glass rod is not stirred, and the local overheating causes the droplets to splash.

The purity is large: when weighing the quality of coarse salt, "left code right thing"; When dissolving, salt water is used instead of distilled water; During filtration, the filter paper leaked, and some of the sediment entered the beaker.

The crude purified NaCl can also be dissolved in a saturated solution prepared by refined salt, so that the heterohail (such as KCL) that is easily soluble in water will be dissolved in the solution, and the NaCl solution itself has reached saturation, so that the operation can precipitate a purer NaCl, and then re-ignite the lead filtration. The leather is good.