INORGANIC DRYING AGENTS

            MOST COMMON INORGANIC DRYING AGENTS

DRYING AGENTS ARE OF TWO TYPES ON THE BASIS OF THEIR  REACTIVITY WITH WATER

1)                Drying agents that react reversibly with water.

2)                Drying reagents that irreversibly react with water.

Following are some the reasons due to which a great deal of care is required while drying reagent selection.

    There are some substances which react with water when we remove water from them drying agents

2    Research data has shown that most of the drying agent violently reacts with water while drying wet solvent with dehydrating agents.

3    Mg(ClO₄)₂ which is a very effective drying agents ,but still not use because of risk of explosions.

Concentrated H₂SO₄,Alkali metals , alkalian earth metals ,Silica gel and molecular sieves are the commonly used dehydrating agent used in chemistry.

Solvent drying agents

For water removal from solvents anhydrous salts are used these are inert and effective drying agents. Examples of such anhydrous salts are MgSO₄, CaCl₂, CaSO₄ etc.

          DRYING AGENTS THAT REACT IRREVERSIBLY WITH WATER

In this category following reagents are included

1     Calcium and Magnesium are used for drying alcohol.

2   Calcium hydride is used for drying a number of solvents but it is not suitable for lower aldehyde and alcohols.

    LiAlH4 is used for hydrocarbons and ethers. Sodium is also used  extensively an efficient  drying agent for removing water from hydrocarbons or ethers, but  sodium also react reacts alcohols, and is not appropriate for drying halogenated solvents.

DRYING AGENTS FOR USE IN DESICCATORS AND DRYING TUBES

The most effective drying agents in this connection are anhydrous CaCl2, CaSO₄, KOH and P₂O₅.

They are the most appropriate agents for drying samples in desiccators. Appropriate drying agents can be used for drying gases , gases are passed   through  drying  tubes  packed  with  a  suitable agent,  but  possible  reaction  of  the  gas  with  the  drying agent must  be  considered.

 The most common drying agent which is used in desiccators is P₂O₅,it react with water results in the formation of a brown, viscous layer on the surface of the  anhydrous  powder,  thereby  shortening  its  dehydrating ability