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能用来测定化学物质酸硷度的指示剂,种类很多。用凤仙花也能够制成一种相当灵敏的指示剂。现在将制法、性能、应用和保存方法介绍于下。取量筒一个,研钵和杵一套,大一点的三角烧瓶一个,玻动棒(或粗铁丝)一根,酒精灯(或油灯)一盏,天平(或秤)一架。准备净水(普通井水就可以)、硫磺粉和新鲜红色凤仙花瓣等原料。在三角烧瓶内倒入一定重量的净水(例如50克),秤取同样重量的凤仙花瓣在研钵里搞碎成浆糊状,加进三角烧瓶内摇匀。用烧灼的玻功棒在瓶内点燃硫磺粉并不断摇动瓶身,加速二氧化硫溶解于水,此时凤仙花瓣碎片渐被漂白。停止燃烧硫粉,待瓶内白烟消失、水色变为淡黄的时候进行过滤,所得淡黄色透明液体即是灵敏的指示剂。此指示剂在酸性溶液里呈红色;在中性溶液中呈淡黄;
There are many types of indicators that can be used to determine the acidity of chemicals. Impatiens can also make a fairly sensitive indicator. Now introduce the method, performance, application and preservation methods. Take one measuring cylinder, one mortar and one mortar, one larger flask, one glass rod (or thick wire), one alcohol lamp (or oil lamp), and one scale (or scale). Prepare clean water (ordinary well water), sulfur powder and fresh red Impatiens petals. Pour a certain amount of clean water (for example, 50g) into the Erlenmeyer flask, and measure the same weight of Impatiens petals in a mortar to make a paste. Add in the Erlenmeyer flask and shake. Burning sulfur powder in the bottle with a burning glass stick and shaking the bottle constantly to accelerate the dissolution of sulfur dioxide in the water, then the petals of Impatiens are gradually bleached. Stop burning the sulfur powder. After the white smoke in the bottle disappears and the water color turns yellowish, filter it. The resulting pale yellow transparent liquid is a sensitive indicator. This indicator is red in acidic solution; it is yellowish in neutral solution;