1. Dissolution: Weigh 5g of raw salt (accurate to 0. 1g) with a tray balance. Measure 10 ml of water with a measuring cylinder and pour it into a beaker. Take a spoonful of raw salt with a medicine spoon and add it to water to observe the phenomenon. Stir with a glass rod and see what happens. 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. Filtering: filtering according to the method described in basic operation 6 of chemical experiment. 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 two times of filtration, the experimental device should be checked and the reasons should be analyzed, such as the damage of filter paper, the liquid level in the funnel is higher than the edge of filter paper during filtration, and the instrument is not clean. After finding out the cause, the operation will be performed.
3. Evaporation: pour the obtained clear filtrate into an evaporating dish. Place the evaporating dish on the iron ring of the iron frame and heat it with alcohol lamp. Meanwhile, the filtrate was continuously stirred with a glass rod. When a large number of solids appear in the evaporating dish, stop heating. The waste heat of the evaporating dish is used to evaporate the filtrate.
Finally, the solid is transferred to the paper with a glass rod, weighed and recycled to the designated container. Compare the salt state before and after purification, and calculate the refined salt output.