The Theory of Quality Separation and Combination
The identification of the common state of the universal substance is related to Kf, and also involves the genus of ions and covalences.

View the composition of the substance, ionic, yin and yang attract each other, and the charge phase is related. If it is a salt, the force of its bond is aggregated due to the charge. Its properties are rigid, and it is easy to separate from water, and it can conduct current.

Covalent, atoms are associated, and electrons are shared, such as various gas elements, or organic substances. Its bonds are flat, and the intermolecular forces are different, whether soft or rigid, and most of them are not induced by water.

To know the number of its Kf is related to the state change. The quality of ions is often different from covalent due to strong bonds. The change of ionic matter in melting and boiling requires breaking strong bonds, so those who can change, Kf is considerable; the quality of covalent matter changes in intermolecular forces, and the number of Kf varies depending on the force.

Scholars have observed that it is essential to analyze the properties of substances, to know their states, to understand the principle of Kf, to distinguish the properties of substances, and to study materials. Therefore, carefully examine the composition of substances, distinguish their ions and covalences, and deduce the number of Kf to obtain the true interpretation of physical properties.