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一、实验原理: 磷酸的第一级电离常数K_1=7.52×10~(-3),而亚硫酸的K_1=1.54×10~(-2),磷酸的酸性比亚硫酸稍弱。所以,当磷酸与亚硫酸钠混和后,混和液中发生了一连串复杂的多步反应,最后达成互相关联的多个平衡。在平衡混和体系中,含有多种酸式盐、酸和正盐。但对于中学生,可以用简化的一个平衡反应式给他们见面: 由于亚硫酸的酸性略强,所以,在通常状况
First, the experimental principle: The first level of phosphoric acid ionization constant K_1 = 7.52 × 10 -3, and K_1 = 1.54 × 10 -2 of sulfurous acid, phosphoric acid is slightly weaker than sulfuric acid. Therefore, when the phosphoric acid is mixed with sodium sulfite, a series of complicated multi-step reactions occur in the mixture, finally reaching a plurality of interconnected balances. In a balanced mixing system, it contains a variety of acid salts, acids and normal salts. But for middle school students, they can be met with a simplified, balanced reaction: As the acidity of sulfurous acid is slightly stronger,