What is the difference between water absorption and deliquescent in chemistry between evaporation an

Deliquescence: Deliquescence is a physical change. Some crystals can spontaneously absorb water vapor in the air and gradually form a saturated solution on their solid surface, if its water vapor pressure is lower than the water vapor pressure in the air, the equilibrium proceeds in the direction of deliquescent, and the water molecules move to the surface of the substance.

This phenomenon is called deliquescent. Anhydrous calcium chloride, magnesium chloride, and solid sodium hydroxide are easily deliquescent in air. Some anhydrous crystals form a saturated solution on the surface after deliquescent, and also become hydrates.

For example, anhydrous calcium chloride becomes CaCl2 6 16H2O after deliquescent; Some only form saturated solutions on the surface, such as sodium hydroxide solids. Because the vapor pressure of the saturated solution of the compound is lower than the partial pressure of the water vapor in the air at the same temperature, the substance continuously absorbs water and deliquescent. The water vapor pressure of the solution is related to the concentration of the solution (of course, it is also related to the ionization of the electrolyte), only the concentration of the saturated solution is large enough to ensure that its water vapor pressure is small enough (less than the water vapor pressure in the air), therefore, deliquescent can occur are those substances with particularly high solubility.

Pure sodium chloride crystals do not deliquescent. At the same time, the occurrence of deliquescent is also related to the relative humidity of the air. Substances that are easy to deliquescent include CaCl2, MgCl2, FeCl3, AiCl3, NaOH and other inorganic salts and alkalis.

Substances that are easily deliquescent are often used as desiccants to absorb water from liquids or gases. Among them, NaOH is only used as a desiccant for neutral or alkaline gases. Substances that are prone to deliquescent must be stored in closed conditions; Drugs that are prone to deliquescent (especially APIs) should be stored under moisture-proof conditions to prevent mildew and deterioration.

Evaporation: is a slow vaporization of a liquid at any temperature that occurs on the surface of the liquid. Meteorology refers to the process by which water turns from liquid to gas.

It can happen at any temperature. For example, in the experiment of extracting refined salt from coarse salt, the water is evaporated. Volatilization:

Generally refers to the liquid components that become gas molecules escaping from the liquid surface without reaching the boiling point. For example, concentrated hydrochloric acid is volatile, etc. Water absorption:

For example, the water absorption of activated carbon. Common substances with water absorption are CuSO4 (which becomes CuSO4 5H2O after water absorption) and sulfuric acid, sodium hydroxide, calcium chloride and magnesium chloride. However, sodium hydroxide will gradually soften in humid air, and in fact, a chemical reaction occurs, and it can also be said that sodium hydroxide is deliquescent.

This is written in a high school textbook.

Water absorption does not necessarily undergo a chemical reaction, whereas deliquescent must undergo a chemical reaction; Evaporation is the process by which a liquid changes from a liquid state to a gaseous state when it reaches a certain temperature, while volatilization is the process by which a substance is separated from a solvent in a gaseous state due to its self-generated nature. Oh.

Water absorption does not necessarily cause a chemical reaction, while deliquescent must laugh at a simulated chemical reaction; Evaporation is the process of changing from a liquid state to a gaseous state when the liquid reaches a certain temperature, while volatilization is the process of separating a substance from a solvent in a gaseous state due to its self-generated properties.