(3)h2so 4+Ba(OH)2 = BaSO 4↓+2H 2 OBa(OH)2+CO2 = BaCO 3↓+H2O
Test question analysis: This is a block diagram inference question, which finds the "test eye" of the problem, including special reaction, special phenomenon, special reaction conditions and common triangular relationship. This test eye catches the outermost two rings in the five rings, because the intersection of circles is required to indicate that it can react, indicating that the substances in these two rings can only react with one of them. After analysis, A is oxygen, so B is iron and C is naturally dilute sulfuric acid. E is carbon dioxide, of course, their order can be reversed, that is, A is carbon dioxide, B is barium hydroxide solution, C is natural dilute sulfuric acid, D is iron, and E is oxygen.
(1) The combination of A and B means that A is oxygen and B is iron. The experimental phenomenon of this reaction is that the silvery white solid (in oxygen or colorless gas) burns violently, and sparks radiate, releasing heat and generating black solid.
(2) Chemical reaction equation with white precipitate: H2SO4+Ba (OH) 2 = Baso4 ↓+H2O or Ba(OH) 2+CO 2 = BaCO 3 ↓+ H2O.