CHROMIUM TRIOXIDE (CRO₃)

SYNONYMS
Chromic acid, chromic anhydride.
CHARACTERISTICS
Dark red, deliquescent crystals or flakes.
INCOMPATIBILITY
Chromium trioxide is incompatible with bases and reducing material causing fire and explosion.
HEALTH HAZARD DATA
This substance can spontaneously combust. It is a strong corrosive substance and can cause severe burns. Kidney damage can result from ingestion. It is a strong oxidising agent and whilst it is not normally combustible it will support combustion. It can be absorbed into the body by inhalation and ingestion. Acute exposure to the skin and eyes causes redness, pain and localised burns. Blurred vision may result. Intensive contact with skin may cause dermatitis. Inhalation may produce sore throat, coughing, shortness of breath and laboured breathing. Ingestion may cause sore throat, abdominal spasm, vomiting and diarrhoea. Potential carcinogen.
HANDLING and GENERAL PRECAUTIONS
Use a fume hood.
Avoid skin and eye contact.
Avoid inhalation or ingestion of the powder.
Keep away from heat.
Keep away from reducing materials.
Keep the lid tightly sealed.
Wash hands thoroughly after handling.
Use a fume hood to keep the level of exposure below the recommended threshold limit, i.e. 0.05 mgm3. If exposure is expected to exceed this limit then a respirator is recommended. Wear protective clothing. A long sleeved laboratory coat or gown, rubber gloves, safety goggles and a face mask as a minimum standard. When making an aqueous solution, if there is any danger of a splash to the face occurring, wear a full face shield.
TREATMENTS
Skin ­ remove contaminated clothing and immediately wash the affected area with large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). If burns develop seek medical attention. Wash contaminated clothing before re­use.
Eyes ­ immediately wash the affected eye with large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). If pain persists or vision is blurred seek immediate medical attention.
Inhalation ­ remove from the area of exposure to fresh air. If breathing has ceased apply artificial respiration. Sit in a half upright position and seek medical attention.
Ingestion ­ rinse the mouth thoroughly with water and give water to drink. Seek immediate medical attention.
STORAGE
Store in a cool, dry atmosphere away from combustible substances and reducing agents.
DISPOSAL
WEAR:
Rubber gloves, face shield and laboratory coat. A body shield should be available for the more active agents. Replace the face shield with self contained breathing apparatus for such agents as chlorine and bromine.
SPILLS:
1. Gas leak - if the valve is leaking because it cannot be closed, the gas can be bubbled through a reducer (sodium sulphite) and excess sodium bicarbonate solution. Be sure to include a trap in the line to prevent the solution being sucked back into the cylinder. If this cannot be done the cylinder should be placed in or adjacent to a fume hood and left to bleed off. If the leak is in the valve assembly, a plastic bag can be fastened over the head of the cylinder which can then be taken outside or to a fume hood.
2. Liquid or solid - cover with a reducer (sodium thiosulphate, a bisulphite or a ferrous salt not carbon, sulphur or strong reducing agent). Mix well and spray with water. A sulphite or a ferrous salt will require addition of 3M sulphuric acid to promote a rapid reduction. Scoop the slurry into a container of water and neutralise with soda ash. Discharge to sewer with a large excess of water. Wash the site thoroughly with a soap solution containing some reducer.
PACKAGE LOTS:
Add to a large volume of concentrated solution of reducer (sodium thiosulphate, a bisulphite or a ferrous salt and acidify with 3M sulphuric acid). When the reduction is completed add soda ash or dilute hydrochloric acid to neutralise the solution. Discharge to sewer with a large excess of water.
ENVIRONMENT

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