A reaction between the reactants, calcium carbide (CaC2) and water. Reactants are the substances which when combined exchange chemical their ions and form other substances. The reaction involves the active ions of the dicarbide (C22-) and the Calcium (Ca2+) with the hydrogen (H+) and the hydroxide ions (OH-) respectively. The ions are formed after the compounds, CaC2 and H2O break up. A compound is a substance formed through the chemical combination of two or more elements in a given ration. Compounds exist as stable substance, which break up when subjected to some chemical forces.
The reaction has the following balanced equation:-
CaC2 + 2 H2O = C2H2 + Ca (OH)2
The breakup of the Calcium and the Carbide ions leaves Calcium to react with the Hydroxide ion as an individual element. An element is substance whose atoms have equal numbers of protons. As such, the element is the simplest substance, which cannot be broken down further by any chemical method.
The above reactions are evident because the reactants produce a certain compound that causes the change in the color of the water. The production of the acetylene gas can be verified by the lighting the opening of the flask within which the chemical reaction is taking place. A glowing splint out at the mouth of the flask lights because acetylene supports combustion.