Sodium hydroxide

  • Caustic soda
  • Soda lye
  • Lye
  • Sodium hydrate
Formula
NaOH
Structure
Description
White, deliquescent pellets or flakes. Hygroscopic.
Uses
Vegetable oil refining, regenerating ion exchange resins, organic fusions, peeling of fruits and vegetables in food industry, etching and electroplating.

Registry Numbers and Inventories.
CAS
1310-73-2
EC (EINECS/ELINCS)
215-185-5
EC Index Number
011-002-00-6
EC Class
Corrosive
S 26 37/39 45
RTECS
WB4900000
RTECS class
Agricultural Chemical and Pesticide; Mutagen; Primary Irritant
UN (DOT)
1823
Merck
12,8772
Beilstein/Gmelin
19031 (G)
EPA OPP
75603
Swiss Giftliste 1
G-4492
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
HNaO
Formula mass
40.00
Melting point, °C
323
Boiling point, °C
1390
Vapor pressure, mmHg
0.07 (300 C)
Saturation Concentration
1980 ppm (0.2%) at 20 C (50 % solution) (calculated)
Odor Threshold Odor threshold Odorless
Density
2.13 g/cm3
Solubility in water
1.1 kg/L
Viscosity
4.0 cp at 350C.
Surface tension
74.35 g/s2 at 18 C
Refractive index
1.412 (420 C)
Dielectric constant
57.5 (25 C)
pKa/pKb
Strong base
Thermal expansion
8.4E-5/K (20 C)
Heat of fusion
8.4 kJ/mol
Heat of vaporization
175 kJ/mol

Hazards and Protection.
Storage
Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Corrosives area. Store protected from moisture. Do not store with aluminum or magnesium. Do not mix with acids or organic materials.
E
Handling
Wash thoroughly after handling. Do not allow water to get into the container because of violent reaction. Minimize dust generation and accumulation. Avoid contact with eyes, skin, and clothing. Keep container tightly closed. Avoid ingestion and inhalation. Use with adequate ventilation. Discard contaminated shoes.
Protection
Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear appropriate protective gloves to prevent skin exposure. Clothing: Wear appropriate protective clothing to minimize contact with skin.
Respirators
If the exposure limit is exceeded and engineering controls are not feasible, a half facepiece particulate respirator (NIOSH type N95 or better filters) may be worn for up to ten times the exposure limit or the maximum use concentration specified by the appropriate regulatory agency or respirator supplier, whichever is lowest.. A full-face piece particulate respirator (NIOSH type N100 filters) may be worn up to 50 times the exposure limit, or the maximum use concentration specified by the appropriate regulatory agency, or respirator supplier, whichever is lowest. If oil particles (e.g. lubricants, cutting fluids, glycerine, etc.) are present, use a NIOSH type R or P filter. For emergencies or instances where the exposure levels are not known, use a full-facepiece positive-pressure, air-supplied respirator.
Small spills/leaks
Vacuum or sweep up material and place into a suitable disposal container. Avoid runoff into storm sewers and ditches which lead to waterways. Clean up spills immediately, using the appropriate protective equipment. Avoid generating dusty conditions. Provide ventilation.
Stability
Stable at room temperature in closed containers under normal storage and handling conditions.
Incompatibilities
Sodium hydroxide in contact with acids and organic halogen compounds, especially trichloroethylene, may causes violent reactions. Contact with nitromethane and other similar nitro compounds causes formation of shock-sensitive salts. Contact with metals such as aluminum, magnesium, tin, and zinc cause formation of flammable hydrogen gas. Sodium hydroxide, even in fairly dilute solution, reacts readily with various sugars to produce carbon monoxide
Decomposition
Irritating and toxic fumes and gases, toxic fumes of sodium oxide, sodium peroxide fumes.

Fire.
Fire fighting
In the event of a fire, wear full protective clothing and NIOSH-approved self-contained breathing apparatus with full facepiece operated in the pressure demand or other positive pressure mode. Use any means suitable for extinguishing surrounding fire. Adding water to caustic solution generates large amounts of heat.
Fire potential
Nonflammable. Not considered to be a fire hazard. Hot or molten material can react violently with water. Can react with certain metals, such as aluminum, to generate flammable hydrogen gas.
Hazards
Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.
Combustion products
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes.
Health
4
 
Flammability
0
 
 
Reactivity
4
 

Health.
Exposure limit(s)
OSHA PEL: TWA 2 mg/m3 NIOSH REL: C 2 mg/m3 NIOSH IDLH: 10 mg/m3
Poison_Class
4
Exposure effects
Prolonged or repeated skin contact may cause dermatitis. Effects may be delayed.
   Ingestion
May cause severe and permanent damage to the digestive tract. Causes gastrointestinal tract burns. May cause perforation of the digestive tract. Causes severe pain, nausea, vomiting, diarrhea, and shock. May cause corrosion and permanent tissue destruction of the esophagus and digestive tract. May cause systemic effects.
   Inhalation
Irritation may lead to chemical pneumonitis and pulmonary edema. Causes severe irritation of upper respiratory tract with coughing, burns, breathing difficulty, and possible coma. Causes chemical burns to the respiratory tract. Aspiration may lead to pulmonary edema. May cause systemic effects.
   Skin
Causes skin burns. May cause deep, penetrating ulcers of the skin. May cause skin rash (in milder cases), and cold and clammy skin with cyanosis or pale color.
   Eyes
Causes eye burns. May cause chemical conjunctivitis and corneal damage.

First aid
 
   Ingestion
Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Get medical aid immediately.
   Inhalation
Get medical aid immediately. Remove from exposure to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. DO NOT use mouth-to-mouth respiration. If breathing has ceased apply artificial respiration using oxygen and a suitable mechanical device such as a bag and a mask.
   Skin
Get medical aid. Flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse. Discard contaminated clothing in a manner which limits further exposure.
   Eyes
Get medical aid. Do NOT allow victim to rub or keep eyes closed. Extensive irrigation is required (at least 30 minutes).

Transport.
UN number
1823
Response guide
Hazard class
8
Packing Group
II
 
USCG CHRIS Code
CSS
 
HS Code
2815 11 00
 
Std. Transport #
4931314
 
IMO Chemical Code
17
IMO Pollution Category
D
IMO Hazard code
S