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水的电离和溶液pH是电解质溶液知识体系的灵魂,理解和熟练掌握有关的基本知识是参透电离平衡理论的保证. 1.水的电离和水的离子积常数水是一种极弱的电解质,它能微弱地电离生成H3O+和OH-,通常简写为H+和OH-.其中c(H+)·c(OH-)=Kw,Kw称为水的离子积常数,简称为水的离子积.其意义是:在一定温度下,水溶液中c(H+)和c(OH-)之积为一常数.由实验测知,在25℃时,1 L纯水中只有约1×10-2mol H2O电离,所以,c(H+)=c(OH-)=1×10-7mol·L-1,因此,在25℃时,Kw=c(H+)·c(OH)=1×10-7×1×10-7=1×10-14(此时的
Ionization of water and solution pH is the soul of the electrolyte system of knowledge, understand and master the relevant basic knowledge is to ensure that penetration of ionization equilibrium theory 1. Ionization of water and water ion constant water is a very weak electrolyte, It weakly ionizes to form H3O + and OH-, which are usually abbreviated as H + and OH-, where c (H +) · c (OH -) = Kw, Kw is called the ionic product constant of water, The meaning is that at a certain temperature, the product of c (H +) and c (OH-) in aqueous solution is a constant, and it has been experimentally found that only about 1 × 10 -2 mol H 2 O in 1 L of pure water is ionized Therefore, at 25 ° C, Kw = c (H +) · c (OH) = 1 × 10-7 × 1, so c (H +) = c (OH -) = 1 × 10-7mol·L- × 10-7 = 1 × 10-14 (at this time