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1990年高考化学试卷第38题:有两瓶 pH=2的酸溶液,一瓶是强酸,一瓶是弱酸。现只有石蕊试液、酚酞试液、pH 试纸和蒸馏水,而没有其它试剂。简述如何用最简便的实验方法来判别哪瓶是强酸:本题意在考查考生对强、弱酸在水中电离程度不同和弱酸的电离度随浓度变化改变的理解,以及运用指示剂去检测溶液酸、碱性强弱的能力。
Chemical examination paper of the 1990 college entrance examination Question 38: There are two bottles of acid solution with pH=2, one bottle is strong acid and one bottle is weak acid. Only litmus test solution, phenolphthalein test solution, pH test paper and distilled water are available. There are no other reagents. Briefly describe how to determine which bottle is a strong acid by the simplest experimental method: This question is intended to examine the candidate’s understanding of the difference in the degree of ionization of strong and weak acids in water and the change in the degree of change of the ionization of weak acids with changes in concentration, and the use of indicators to detect solutions. Acid, alkaline strength.