(齐陵一中----刘翠红)(5分)为了比较不同水果中维生素C的含量,某同学设计了

题型:探究题

问题:

(齐陵一中----刘翠红)(5分)为了比较不同水果中维生素C的含量,某同学设计了如下实验:

⑴任选两种水果A和水果B。将水果切碎放到研钵中挤出汁液或用榨汁机榨出汁液。

⑵.将这两种新鲜的汁液分别倒入两个洁净、干燥的小烧杯中。

⑶.取2支洁净、干燥的试管,分别注入________的高锰酸钾溶液约2毫升。

⑷. 取一支洁净、干燥的滴管,吸取水果A汁液,逐滴地滴入试管中,边滴、边振荡、边观察。当高锰酸钾溶液褪去颜色后记录下汁液的滴数。

⑸.参照上面的方法,用上述滴管测试水果B汁液,记录下汁液的滴数并与水果A汁液的滴数进行比较,就可以得出结论了。

记录结果如下:

水果的名称滴入的汁液的滴数
A9
B11
 

请分析回答:

⑴补充实验步骤⑶。

⑵记录结果说明________比________的维生素C含量高。

⑶为了便于准确地比较,应当使用______滴管滳两种汁液。使用滴管滴第二种汁液前,需要_____________,并用_______吸干滴管内外的水分。

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