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向过量的醋酸溶液中滴加碳酸钠溶液,会看到有大量气泡产生,反应的化学方程式为Na_2CO_3+2CH_3COOH→2CH_3COONa+H_2O+CO_2↑,但是向过量的碳酸钠溶液中滴加醋酸溶液并振荡,却观察不到明显现象,原因是反应所生成的二氧化碳与过量的碳酸钠反应,生成了难电离的碳酸氢根离子,有关的离子方程式为CO_2+H_2O+CO_3~(2-)=2HCO_3~-。从该实验说明了醋酸的电离能力大于碳酸的第一步电离(醋酸电离常数Ka=1.75×10~(-5),碳酸的第一步电离常数Ka_1=4.30×10_(-7)。将含苯酚量适当大于其溶解度的混浊的含水苯酚滴入碳酸钠溶液中,溶液变澄清,但滴至过量,并无气泡产生,其反应的化学方程式为(?)—OH+Na_2CO_3→(?)—ONa+NaHCO_3,而取苯酚在氢氧化钠中的饱和溶液通入二氧化碳,溶液变混
A solution of sodium carbonate is added dropwise to the excess acetic acid solution, and a large number of bubbles are observed. The chemical equation of the reaction is Na 2 CO 3 + 2 CH 3 COOH → 2 CH 3 COONa + H 2 O + CO 2 , but the acetic acid solution is added dropwise to the excess sodium carbonate solution and oscillated. However, no observable phenomenon was observed because the carbon dioxide generated by the reaction reacted with excess sodium carbonate to generate hydrogen ionized bicarbonate ions. The related ion equation is CO 2 +H 2 O +CO 3 -2 -=2HCO 3 - -. From this experiment, it was shown that the ionization capacity of acetic acid is greater than the first ionization of carbonic acid (acetic acid ionization constant Ka=1.75×10-5, and the first ionization constant of carbonic acid Ka_1=4.30×10−(-7). The turbid aqueous phenol with a phenol content more than its solubility is dropped into the sodium carbonate solution, the solution becomes clear, but it is dripped to excess, and no bubbles are generated. The chemical equation of the reaction is (?)-OH+Na_2CO_3→(?)— ONa + NaHCO 3 , and the saturated solution of phenol in sodium hydroxide is fed with carbon dioxide, and the solution is mixed