1. Weigh 2g of raw salt (accurate to 0. 1g) with a tray balance for dissolution. Measure 10ml of water with a measuring cylinder and pour it into a beaker. Add a spoonful of crude salt to the water with a medicine spoon and observe what will happen. Stir with a glass rod and observe what happens (what effect does the stirring of the glass rod have on the dissolution of the original salt? Stirring to accelerate dissolution). Then add the original salt and stir with a glass rod while adding it until the original salt is no longer dissolved. Observe whether the solution is turbid. Weigh the remaining raw salt on the balance and calculate how many grams of raw salt are dissolved in 10 ml of water.
2. filter. 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. 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, the end of the glass rod should be close to the side with three layers of filter paper, and the end of the funnel should be close to the inner wall of the beaker for holding filtrate. Pour the liquid slowly. When there is no water on the filter paper, carefully observe the residue on the filter paper and the color of the filtrate. When the filtrate is still turbid, it should be filtered again. If the filtrate is still turbid after filtering twice, check the equipment and analyze the reasons, such as the damage of filter paper, the liquid level in the funnel is higher than the edge of filter paper during filtering, and the instrument is unclean. After finding out the reason, the operation should be resumed.
3. Evaporation. Pour the clarified filtrate into an evaporating dish. Place the evaporating dish on the iron ring of the iron frame and heat it with alcohol lamp. At the same time, the filtrate is continuously stirred with a glass rod (evenly heated to prevent the liquid from splashing). When a large number of solids appear in the evaporating dish, stop heating. Evaporating the filtrate by using the waste heat of the evaporating dish.
4. Transfer the solid to the paper with a glass rod, weigh it and recycle it to the container designated by the teacher. Compare the salt state before and after purification, and calculate the refined salt output.