A deliquescent material absorbs or releases water vapor to the atmosphere to maintain a constant vapor pressure of water at a given temperature. For example, if a saturated aqueous solution of a deliquescent material has a lower water vapor pressure than that of the atmosphere, moisture will condense into the solution until the solution water vapor matches the atmospheric water vapor. Some deliquescent materials are: concentrated sulfuric acid, glycerol, calcium chloride, sodium hydroxide pellets, anhydrous sodium sulfate and potassium carbonate. Many of the solid compounds will absorb enough water from the air to dissolve into a saturated liquid. The opposite phenomenon is called efflorescence.
Sources Checked for Data in Record
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
- Theodore J. Reinhart, 'Glossary of Terms', Engineered Plastics, ASM International, 1988