The mastery of chemical equations in senior high school is not to recite as many as possible, but to classify and grasp the reaction principle of each kind, from the outside to the inside, from the shallow to the deep, from the individual to the general. Here I classify them as follows: (1) There are (1) four basic reactions in inorganic field: combination, decomposition, replacement and double decomposition (2) redox reaction. Zinc reacts with dilute hydrochloric acid, heating potassium chlorate to generate oxygen, and introducing chlorine into calcium hydroxide solution to generate bleaching powder, hydrogen sulfide and sulfur dioxide (corresponding to one example according to the above classification). (3) Ion reaction: the reaction between ions, and any metathesis reaction between acid, alkali and salt must obey the condition that metathesis is carried out to the end. Reactions between ions and molecules; For example, the reaction between chlorine and iodine ion, and the reaction between sulfide and acid, alkali and salt. A reaction between ions and electrons, such as hydroxyl ions losing electrons at the anode. An electrolytic reaction in an aqueous solution, for example, electrolysis of an aqueous solution of sodium chloride to produce hydrogen and chlorine. Coordination reaction in aqueous solution. (4) Salt hydrolysis: hydrolysis of strong acid and weak base salt, hydrolysis of strong base and weak acid salt, hydrolysis of weak acid and weak base salt, double hydrolysis reaction, etc. (5) Reversible reaction and movement of reversible equilibrium (6) Exothermic reaction and endothermic reaction. (2) Organic reactions include (1) substitution, addition, organic redox, intramolecular dehydration, intermolecular dehydration, polymerization (polyaddition and polycondensation), halogenation, sulfonation, nitration, cracking, elimination, hydrolysis, esterification, coloration, high-temperature carbonization, hydration, etc. You must master the principle of each reaction, the characteristics of each substance, the conditions and mutual reactions of each reaction, and study the inevitable laws between them. I think you can learn chemistry well. I wish you success!