Main distinction – Deliquescent vs Efflorescent vs Hygroscopic

Some substances deserve to undergo physical changes when castle are kept in an open place. This is as result of absorption or adsorption that water vapor or release of water molecules from their structure. There is around 0-4% that water vapor in the air, depending upon the location and the time the the day. Deliquescent substances space solids that can get dissolved by soaking up water vapor. Yet this absorption relies on the humidity the the environment. Efflorescent substances are crystals that have the right to lose water molecules that are already present in your molecular structure. Hygroscopic substances space another type of solid matter that deserve to either absorb or adsorb water vapor native the atmosphere. But these substances carry out not dissolve after ~ the absorption. The main difference between deliquescent efflorescent and also hygroscopic building material is that deliquescent substances form an aqueous systems by soaking up water vapor when efflorescent substances carry out not absorb water vapor and hygroscopic substances deserve to absorb water vapor, yet they do not kind an aqueous solution.

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Key locations Covered

1. What is Deliquescent – Definition, Process, Examples 2. What is Efflorescent – Definition, Process, Examples 3. What is Hygroscopic – Definition, Process, Examples 4. What is the Difference in between Deliquescent Efflorescent and HygroscopicComparison of key Differences

Key Terms: Deliquescence, Deliquescent Substance, Efflorescence, Efflorescent Substances, Hygroscopic Substances, Hygroscopy, Water Vapor


What is Deliquescent

Deliquescent substances room solid matter that can get dissolved by absorbing water vapor. The resulting equipment is one aqueous solution. This process is known as deliquescence. These deliquescent substances have actually a high affinity to water.

The setting has 0-4% that water vapor, depending on the location and also the time that the day. Due to the fact that there are numerous other gases and also vapors in the atmosphere, water vapor has a partial pressure. Deliquescence happens when the vapor push of the equipment that is walking to kind is much less than the partial pressure of water vapor in the air.

Humid atmospheres are highly concentrated with water vapor. Therefore, deliquescent substances can easily undergo deliquescence and type solutions by taking in a high lot of water vapor when they are put in a humid environment.


Figure 1: NaOH pellets can absorb water vapor indigenous the air

Most typical examples that deliquescent substances incorporate some salts; for example, salt hydroxide, potassium hydroxide, ammonium chloride, salt nitrate, calcium chloride, etc. This substances deserve to be provided as desiccants. As soon as the water vapor inside a container needs to be gotten rid of in order to protect against a details chemical reaction, these substances can be maintained inside the container. Climate the deliquescent substances will absorb a high amount of water and also prevent the interferences coming from water vapor.

What is Efflorescent

Efflorescent substances are solids that deserve to undergo spontaneous lose of water indigenous hydrated salts. Hydrated salts are not natural salts include water molecules linked in a identify ratio. These salts deserve to lose these water molecules once kept outside. This process is known as efflorescence.

Efflorescence occurs once the aqueous vapor pressure of the hydrate is greater than the partial press of the water vapor in the air. Efflorescent substances incorporate most sign language salts. Examples encompass Na2SO4, 10H2O, Na2CO3, 10H2O, and also FeSO4. A common example the efflorescence is dry of cement.


Figure 2: Calcium Sulfate Efflorescence

However, as soon as these water molecules are shed from the sign language salt, the salt mirrors a powdery surface because of the ns of water. Eventually, the salt crystals will continue to be in the container. The phase of water is changed to the gaseous phase.

What is Hygroscopic

Hygroscopic substances are solids that deserve to absorb or adsorb water native its surroundings. As soon as water vapor is took in by hygroscopic substances, the water molecules are taken right into the spaces that the crystal structure. This reasons the volume that the problem to increase. Hygroscopy can result in changes in the physical properties that the hygroscopic substances; such properties include color, boil point, viscosity, etc.


Figure 3: Zinc Chloride Powder

Most instances of hygroscopic substances incorporate salts. Some examples are Zinc chloride (ZnCl2), salt chloride (NaCl) and also sodium hydroxide (NaOH). Over there are likewise some other typical substances we know as hygroscopic. This compounds encompass honey, silica gel, germinating seeds, etc.

Difference between Deliquescent Efflorescent and also Hygroscopic


Deliquescent: Deliquescent substances space solids that absorb moisture from the atmosphere until castle dissolve in the took in water and kind solutions.

Efflorescent: Efflorescent substances space solids that deserve to undergo spontaneous lose of water from hydrated salts.

Hygroscopic: Hygroscopic substances room solids that deserve to absorb or adsorb water from its surroundings.

Water Vapor Absorption

Deliquescent: Deliquescent substances can absorb a high amount of water vapor.

Efflorescent: Efflorescent substances do not absorb water vapor.

Hygroscopic: Hygroscopic substances deserve to either absorb or adsorb water vapor.

Other Names

Deliquescent: Deliquescent substances are called desiccants.

Efflorescent: Efflorescent substances space crystals.

Hygroscopic: Hygroscopic building materials are referred to as humectants.

Affinity because that Water

Deliquescent: Deliquescent substances have actually a really high affinity for water.

Efflorescent: Efflorescent substances have actually no significant affinity for water.

Hygroscopic: Hygroscopic substances have actually a less affinity for water.

Formation that a Solution

Deliquescent: Deliquescent substances type an aqueous equipment by soaking up water vapor.

Efflorescent: Efflorescent substances carry out not type a solution.

Hygroscopic: Hygroscopic substances execute not kind a solution, yet absorb water vapor.


Some compounds can absorb water vapor whereas some compounds deserve to release water as water vapor. This ability depends top top the molecular structure of the compound and also environmental factors. Follow to this ability, substances have the right to be divided into three various groups as deliquescent substances, efflorescent substances, and also hygroscopic substances. Deliquescent substances kind an aqueous systems by absorbing water vapor, and also efflorescent substances do not absorb water vapor whereas hygroscopic substances deserve to absorb water vapor but they execute not kind an aqueous solution. This is the simple difference in between deliquescent efflorescent and hygroscopic.

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1. Helmenstine, ann Marie. “Hygroscopic versus Hydroscopic.” ThoughtCo, easily accessible here. 2. “Efflorescence.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 12 Apr. 2007, obtainable here. 3. Helmenstine, anne Marie. “Chemistry Glossary meaning of Deliquescence.” ThoughtCo, available here.

Image Courtesy:

 1. “SodiumHydroxide” by Walkerma – Own occupational (Public Domain) via Commons Wikimedia 2. “Calcium sulfate efflorescence” by Eurico Zimbres (CC BY-SA 2.5) via Commons Wikimedia 3. “Zinc chloride” by User:Walkerma – Own work-related (Public Domain) via Commons Wikimedia