Handle with care: Commonly used lab reagents and their hazards

Author: Abdul Wahab M Kannde

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I am continuing the series of chemicals & safety which I started last week, hope you find it useful, just give a comment to tell me how you handle these chemicals.

DO

• Use the appropriate size container for the job.
• Get help when needed.
• Clean containers after use with deionized water.
• Work under a fume hood unless you have been told otherwise by the lab manager/supervisor.
• Use a funnel when pouring chemicals into a small container.
• Open bottles slowly to avoid spilling and allow vapors to escape.
• Know what type of reactions to expect.
• Remember to triple-A (AAA): Always Add Acid to water.

DON'T

• Reuse containers (adverse chemical reaction may occur).
• Eat, drink, smoke, or touch any body part before washing your hands when working with chemicals.
• Be afraid to ask questions.
• Pour leftover chemicals back in its source container, contamination may result.
• Put your face close to the bottle when pouring.
• Puncture cap or lid of any bottle.

 

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Commonly used lab reagents & their hazards

Acetic Acid CH₃COOH, Concentrated acetic acid is corrosive and must therefore be handled with appropriate care, since it can cause skin burns, permanent eye damage, and irritation to the mucous membranes. These burns or blisters may not appear until hours after exposure. Reacts vigorously with oxidizing agents and other acids (particularly nitric). Odor similar to that of strong vinegar (do not smell it, strong odour). Incompatible with most other acids. Store seperately!  

Chromic Acid H₂CRO₄ Liquid and vapors cause severe burns to skin. Corrosive to nasal passages. Contains a suspected carcinogen. Carcinogenic.

Hydrochloric Acid HCl Concentrated hydrochloric acid (fuming hydrochloric acid) forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. Repeated exposure causes erosion of teeth. Strong chlorine odor detectable at 1-5 PPM. 

Hydrofluoric Acid HF Hydrofluoric acid is corrosive and a contact poison. It should be handled with extreme care, beyond that accorded to other mineral acids, in part because of its low dissociation constant, which allows HF to penetrate tissue more quickly. Symptoms of exposure to hydrofluoric acid may not be immediately evident. HF interferes with nerve function and burns may not initially be painful. Liquid and vapors cause burns that may not be immediately painful or visible. HF attacks glass. Found in Buffered Oxide Etch (BOE). Use only plastic containers.

Nitric Acid HNO₃ Nitric acid is a powerful oxidizing agent, and the reactions of nitric acid with compounds such as cyanides, carbides, and metallic powders can be explosive. Reactions of nitric acid with many organic compounds, such as turpentine, are violent and hypergolic (i.e., self-igniting). Concentrated nitric acid dyes human skin yellow due to a reaction with the keratin. These yellow stains turn orange when neutralized. Highly corrosive to skin, mucous membranes and teeth. Use only glass containers.

Phosphoric Acid H₃PO₄ Liquid is highly irritating to skin. Vapors are highly toxic. Contact with most metals causes formation of flammable and explosive hydrogen gas. 

Sulfuric Acid H₂SO_4­, The corrosive properties of sulfuric acid are accentuated by its highly exothermic reaction with water. Hence burns from sulfuric acid are potentially more serious than those of comparable strong acids (e.g. hydrochloric acid), as there is additional tissue damage due to dehydration and particularly due to the heat liberated by the reaction with water; i.e. secondary thermal damage. The danger is obviously greater with more concentrated preparations of sulfuric acid, but it should be remembered that even the normal laboratory "dilute" grade (approx. 1 M, 10%) will char paper by dehydration if left in contact for a sufficient time. Solutions equal to or stronger than 1.5 M should be labeled CORROSIVE, while solutions greater than 0.5 M but less than 1.5 M should be labeled IRRITANT. Liquid and vapors are extremely corrosive to skin and mucous membranes. Generates heat upon contact with water. Keep away from water

Sodium Hydroxide NaOH, Solid sodium hydroxide or solutions containing high concentrations of sodium hydroxide may cause chemical burns, permanent injury or scarring, and blindness. Dissolution of sodium hydroxide is highly exothermic, and the resulting heat may cause heat burns or ignite flammables. Sodium hydroxide is extremely caustic, and can react with fats and oils on skin, in a reaction which creates salts. For this reason, sodium hydroxide is very dangerous, and skin should be washed thoroughly with water following contact with this substance. A solution of 0.5 M or more of sodium hydroxide should be labeled corrosive, while a solution between 0.5-0.05 M should be labeled irritant.

Ammonium Fluoride NH₄F Highly toxic and irritating to skin and mucous membranes. Emits toxic vapors when heated or when in contact with acids.  

Ammonium compounds should never be allowed to come in contact with bases (unless in an intended and contained reaction), as dangerous quantities of ammonia gas could be released.

Hydrogen Peroxide H₂O₂ Strong oxidizing agent. Irritating to skin and mucous membranes. Reacts violently with acids and organic solvents.  Cap with vented cap. Do not boil in open vessels, may cause explosion.  Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure. Concentrated hydrogen peroxide, if spilled on clothing (or other flammable materials), will preferentially evaporate water until the concentration reaches sufficient strength, at which point the material may spontaneously ignite. Large oral doses of Hydrogen peroxide on a 3% concentration may cause "irritation and blistering to the mouth, throat, and abdomen", as well as "abdominal pain, vomiting, and diarrhea".

Phosphorous Oxychloride POCl₃ POCI3 and its vapors cause severe burns to the eyes, nose, throat, skin and mucous membranes. POCI₃ and water, when combined, will form hydrochloric acid and will produce a violent, exothermic reaction. POCI₃ is unstable at high temperatures.  Keep away from water. Discard gloves discolored by POCI₃. Discard yellow or cloudy POCI₃ as it may be contaminated. 

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