Calcium acetate exists because it is stable at room temperature without double hydrolysis. The solid of calcium acetate can't be obtained when the solution of CH3COOO-+H2O = = = = CH3COOOH+OH-calcium acetate is heated, evaporated and crystallized, which is extracurricular knowledge, but it is not easy to obtain when the solution is evaporated. Calcium acetate solid is usually prepared by cooling with hot saturated solution, because calcium acetate will decompose, and the generated acetone gas and calcium carbonate (ch 3c oo)2Ca = = = = = = = = = heating = = = = = = = = CaCO3+Ch3coch3 ↑ (boiling point 50 degrees) exist or not, and the reason why aluminum carbonate and iron carbonate do not exist is that double hydrolysis occurs. The generated aluminum hydroxide or iron hydroxide, water and carbon dioxide can not react again to generate aluminum carbonate or iron carbonate, so the double hydrolysis reaction is irreversible, and it is judged that the substance does not exist. However, calcium hydroxide is a strong alkali among medium alkali and strong alkali. Calcium acetate can react again after hydrolysis and the reaction is reversible, so calcium acetate exists.