1/2 Rule:Semi Quantitative Determination Method for Acidity of Oxyacid Based on Lewis Structural Formula
ZHANG Shi-Man1*, LI Cun-Pu2
1. Chongqing Foreign Language School, Chongqing 400039,China;
2. School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China
Abstract A semiquantitative method was constructed to compare and evaluate the acidity of oxoacids via the valence-bond-theory based Lewis structures, which was referred to as the “1/2 rule”. Density functional theory calculations were performed to evaluate the reliability and feasibility of the “1/2 rule”. The acidities of common oxoacids, stepwise ionization behavior of polyatomic acids, as well as the evolutionary tendencies of the oxoacids of multivalent elements, can be calculated with the constructed “1/2 rule”. The students can understand the regularities of oxoacids by the introduction of the “1/2 rule”. Therefore, rote-learning can be transformed into reasoning-understanding. Students can gradually dip into the chemical “structure-energy-property” logical system and understand the critical competence “macroscopic identification and microscopic reasoning” via the leaning of the “1/2 rule”.
ZHANG Shi-Man, LI Cun-Pu. 1/2 Rule:Semi Quantitative Determination Method for Acidity of Oxyacid Based on Lewis Structural Formula[J]. Chinese Journal of Chemical Education, 2021, 42(7): 68-71.