Silicon

Formula
Si
Structure
Description
A dark brown powder.
Uses
For making silanes & silicones, manufacture of transistors, silicon diodes, semiconductors, for making alloys such as ferrosilicon, silicon bronze, silicon copper, reducing agent in high temp reaction.

Registry Numbers and Inventories.
CAS
7440-21-3
EC (EINECS/ELINCS)
231-130-8
RTECS
VW0400000
RTECS class
Primary Irritant
UN (DOT)
1346
Merck
12,8635
Beilstein/Gmelin
61188 (G)
Swiss Giftliste 1
G-8568
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Korea ECL
Listed

Properties.
Formula
Si
Formula mass
28.08
Melting point, °C
1410
Boiling point, °C
2355
Density
2.34 g/cm3
Solubility in water
Insoluble
Surface tension
736 g/s2 @ MP
Heat of vaporization
449 kJ/mol
Heat of combustion
-9055 kJ/mol

Hazards and Protection.
Storage
Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Store protected from moisture.
Handling
Minimize dust generation and accumulation. Avoid contact with skin and eyes. Avoid ingestion and inhalation. Do not allow contact with water. Use only in a chemical fume hood. Keep from contact with moist air and steam.
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 a chemical apron. Wear appropriate protective clothing to prevent skin exposure.
Respirators
A NIOSH/MSHA approved air purifying dust or mist respirator or European Standard EN 149.
Small spills/leaks
Vacuum or sweep up material and place into a suitable disposal container. Very fine particles can cause a fire or explosion. Eliminate all ignition sources. Clean up spills immediately, using the appropriate protective equipment. Avoid generating dusty conditions. Provide ventilation. Do not get water inside containers.
Stability
Stable under normal temperatures and pressures.
Incompatibilities
Moisture, strong oxidizing agents.
Decomposition
Irritating and toxic fumes and gases, oxides of silicon.

Fire.
Autoignition, °C
>150
Fire fighting
Wear a self-contained breathing apparatus in pressure-demand, MSHA/NIOSH (approved or equivalent), and full protective gear. Dusts at sufficient concentrations can form explosive mixtures with air. Dousing metallic fires with water may generate hydrogen gas, an extremely dangerous explosion hazard. To extinguish fire use water spray, dry chemical, carbon dioxide, or chemical foam. Do NOT get water inside containers.
Hazards
May react violently or explosively on contact with water. Some are transported in flammable liquids. May be ignited by friction, heat, sparks or flames. Some of these materials will burn with intense heat. Dusts or fumes may form explosive mixtures in air. Containers may explode when heated. May re-ignite after fire is extinguished.
Health
1
 
Flammability
0
 
 
Reactivity
0
 

Health.
Exposure limit(s)
NIOSH REL: TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp) OSHA PEL: TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)
Poison_Class
-
Exposure effects
Chronic inhalation of dust may lead to silicosis. May cause silicosis-disabling pulmonary fibrosis characterized by fibrotic changes and miliary nodules in the lungs, dry cough, shortness of breath, emphysema, decreased chest expansion and increased susceptibility to tuberculosis.
   Ingestion
May cause irritation of the digestive tract.
   Inhalation
May cause respiratory tract irritation. Contains crystalline silica which may lead to respiratory abnormalities and silicosis.
   Skin
May cause skin irritation.
   Eyes
May cause eye irritation.

First aid
 
   Ingestion
Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Get medical aid.
   Inhalation
Remove from exposure to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical aid if cough or other symptoms appear.
   Skin
Flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Get medical aid if irritation develops or persists. Wash clothing before reuse.
   Eyes
Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid.

Transport.
UN number
1346
Response guide
Hazard class
4.1
Packing Group
III
 
Std. Transport #
4917481