Materials

PROPER AND SAFE HANDLING OF CHEMICALS

Handling Flammable Reagents

• Never handle flammable reagents near open flames.

  • Examples:

    • hexane

    • petroleum ether (petroleum benzene, ligroin, or light petroleum)

    • alcohols

    • ethyl acetate

    • acetone

    • benzene

    • carbon disulfide

    • toluene

    • diethyl ether

Handling Explosive Reagents

• Explosive reagents should never be handled with water.

  • Store in kerosene or mineral oil.

  • Use forceps instead of bare hands.

  • Examples:

    • sodium metal

    • potassium metal and other group IA metals

Handling White Phosphorous

• Store white phosphorous in water.

• Always cut under water and use forceps to handle.

Carcinogenic Chlorocarbons

• Chlorocarbons (CCl4 and CHCl3) are liver carcinogens.

• Minimize exposure whenever possible.

Handling Carbon Disulfide

• Carbon disulfide burns easily even at temperatures below 100ºC.

• Exercise caution during heating procedures with this chemical.

Strong Oxidizing Agents

• Never let strong oxidizing agents contact organic materials.

• This can cause fires.

• Examples:

  • nitric acid

  • hydrogen peroxide

  • sulfuric acid

  • potassium permanganate

Handling Corrosive Agents

• Use industrial gloves when handling corrosive agents.

• Examples:

  • sulfuric acid

  • sodium and potassium hydroxide

  • hydrochloric acid

  • sodium carbonate

  • phosphoric acid

  • ammonia

  • nitric acid

  • bromine

  • carboxylic and sulfonic acids

  • thionyl chloride

Fume Hood Safety

• Handle harmful and toxic reagents under a fume hood.

  • Examples:

    • aniline

    • methanol

    • benzene

    • nitrobenzene

    • bromine

    • phenol

    • carbon tetrachloride

    • phenylhydrazine

    • hydrogen sulfide

    • sodium and potassium cyanide

    • dimethyl sulfate

    • elementary mercury

• Cancer suspect agents should also be handled under a fume hood.

  • Examples:

    • dimethyl sulfate

    • phenylhydrazine

    • formaldehyde

    • carbon tetrachloride

    • benzene

    • chloroform

Handling Cyanides

• Solutions of cyanides must never contact acids.

• Toxic HCN will be liberated.

Skin Staining Agents

• Handle skin staining substances with gloves.

• Examples:

  • picric acid

  • methyl violet

  • malachite green

Mercury Disposal

• Elemental and soluble mercury compounds should never be disposed of in the sink.

• Dispose in a separate waste bottle (white container).

Volatile Chemicals

• Do not work near flame or hot plates with highly volatile chemicals.

  • Examples:

    • diethyl ether

    • carbon disulfide

    • chloroform

General Chemical Handling Tips

• Ensure reagent caps are tightly screwed after use.

• Carry large bottles of chemicals with both hands.

  • Grasp the neck with one hand and support the bottom with the other.

• Never use an unlabeled chemical.

• Do not perform taste tests in the laboratory unless instructed.

• Avoid pointing test tubes at others while contents are boiling.

• Do not mix strong oxidizing agents with reducing agents without instructions.

PROPER CONTAINERS AND STORAGE FOR CHEMICALS

Alkali Solutions

• Alkali solutions must not be stored in glass containers.

• This prevents leaching and freezing of stoppers.

• Use cork or rubber stoppers instead.

Light-sensitive Solutions

• Store light-sensitive solutions in amber-colored bottles.

  • Examples:

    • potassium permanganate

    • iodine

    • oxalic acid

    • ferrous and ferric salts

    • sodium thiosulfate

    • silver nitrate

    • ceric sulfate

Ferrous Salts Storage

• Solutions of ferrous salts must remain acidic.

• This prevents air-oxidation to ferric state.

• Rate of oxidation increases with higher pH.

Fresh Preparation of Solutions

• Ferrous and ferric solutions should be freshly prepared.

Special Storage for Chlorine and Bromine Water

• Chlorine and bromine water deteriorate on standing.

• Store in amber bottles and prepare fresh.

Small Quantity Preparation

• Prepare solutions in small quantities when needed.

PROPER DISPOSAL OF CHEMICALS

Disposal Protocols

1. Do not dispose of organic solvents and noxious chemicals in the sink.

2. Neutralize acids with technical grade sodium carbonate, dilute with water, and then drain into the sink.

3. Unreacted sodium or potassium metal must be reacted with excess ethanol before disposal.

4. Unreacted white phosphorus should be oxidized to phosphate ions with nitric acid prior to disposal.

5. Attend to spills immediately:

   • Notify the teacher for microbiological cultures.

   • Neutralize spills of acids with sodium bisulfate.

   • Neutralize spills of bases with sodium bisulfate.

   • Absorb neutral solvents with sand or paper towels; sand is preferred.

   • For volatile liquids, clear the area, extinguish flames, and allow evaporation.

Chemical Categories for Disposal

• Halogenated Compounds:

  • Chloroform

  • Carbon tetrachloride

  • Benzyl chloride

  • Chlorobenzene

• Nonhalogenated Compounds:

  • Ethyl acetate

  • Benzene

  • Ethanol and methanol

• Metal Residues:

  • mercury

  • zinc dust