Sodium hydroxide
Redirected from Lye
Sodium hydroxide (NaOH), also known as caustic soda or lye, is a caustic[?] hydroxide used in industry (mostly as a strong chemical base) in the manufacture of paper, textiles, and detergents.
Sodium hydroxide is occasionally used in the home as an agent for unclogging stuck drains, but it is highly corrosive and has a high danger of causing chemical burns[?], permanent injury or scarring, and blindness, due to its high reactivity[?].
When sodium hydroxide reacts with water, it can become hot enough to cause fires.
For this reason, it is important to have the proper type of chemical fire extinguisher on hand before working with sodium hydroxide.
Sodium hydroxide is manufactured by electrolysis of an aqueous solution of sodium chloride.
It is a by-product of the process that is used to make chlorine.
A solution of a small portion of lye diluted in water is used in the traditional method of making a pretzel.
General
Name
Sodium hydroxide
Chemical formula
NaOH
Appearance
White solid
Physical
Formula weight
40.0 amu
Melting point
596 K (323 °C)
Boiling point
1663 K (1390 °C)
Density
2.1 ×103 kg/m3
Crystal structure
?
Solubility
?
Thermochemistry
ΔfH0gas
-197.76 kJ/mol
ΔfH0liquid
-416.88 kJ/mol
ΔfH0solid
-425.93 kJ/mol
S0gas, 1 bar
228.47 J/mol·K
S0liquid, 1 bar
75.91 J/mol·K
S0solid
64.46 J/mol·K
Safety
Ingestion
May cause severe and permanent damage to the GI system.
Inhalation
Irritation for low exposures, may be harmful or fatal in higher doses.
Skin
Dangerous. Symptoms range from mild irritation to nasty ulcers.
Eyes
Dangerous. May cause burns, damage to cornea or conjuctiva.
More info
Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/8/7069.html)
SI units were used where possible. Unless otherwise stated, standard conditions were used.