题干

 化学小组在做实验时,不小心将固体食盐中混入了氢氧化钠,但不知是否又混入了氢氧化钙和碳酸钙中的一种或两种,请按要求回答问题:
(1)确定成分:

实验操作实验现象实验结论
 ____  ____ 没有混入碳酸钙
 ____  ____ 混入了氢氧化钙

(2)除去杂质:
①将余下的固体药品放入大烧杯中并向其中加入足量的蒸馏水,使其完全溶解,再向烧杯中加入过量的____ ,目的是____ ,最后进行过滤。
②向实验①所得的滤液中加入过量的____ 。
③将实验②所得的溶液采用____ 的方法,便可以得到纯净的食盐固体。

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    Art is considered by many people to be no more than a decorative means of giving pleasure. This is not always the case, however, at times, art may be seen to have a purely functional side as well. Such could be said of the sandpaintings of the Navaho Indians of the American Southwest; these have a medicinal as well as an artistic purpose.

    According to Navaho traditions, one who suffers from either a mental or a physical illness has in some way disturbed or get in touch with the supernatural—perhaps a certain animal, a ghost, or the dead. To break away from this, the ill person or one of his relatives will employ a medical man called a "singer" to perform a curing ceremony which will attract a powerful supernatural being. During the ceremony, which may last from 2 to 9 days, the "singer" will produce a sandpainting on the floor. On the last day of the ceremony, the patient will sit on this sandpainting and the "singer" will rub the sick or injured parts of the patient's body with sand from a specific figure in the sandpainting. In this way the patient absorbs the power of that particular supernatural being and becomes strong. After the ceremony, the sandpainting is destroyed so its power won't harm anyone.

    The art of sandpainting is handed down from old "singers". The materials used are easily found where the Navaho settle: brown, red, yellow, and white sandstone, which is ground(研磨)much as corn is made into flour. The "singer" holds a small amount of this sand in his hand and lets it flow between his fingers onto a clean, flat surface on the floor, with a steady hand and great patience. He is thus able to create designs of stylized people, snakes and other creatures that have power in the Navaho belief system. The traditional Navaho doesn't allow copying sandpaintings, since he believes the supernatural powers that taught him the craft have forbidden this; however, such reproductions can in fact be purchased today in tourist shops in Arizona and New Mexico. These are done by either Navaho Indians or by other people who wish to preserve this craft.