FINDING VITAL INFORMATION ON CHEMICALS

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Everything around us and within us is a chemical, the air we breathe, the food we eat, our bodies. Every thing is a chemical.  There are over 9 million compounds in the ACS Chemical Abstracts Registry and over 75,000 are in common use throughout the world.             This exercise will introduce you to correct handling procedures of chemicals, precautions about their use, and correct methods of disposal.  You will learn how to find information about chemicals from their labels and Material Safety Data Sheets (MSDS).

 

Material Safety Data Sheets (MSDS)

            MSDS are furnished by chemical suppliers and provide information about:

1. Identity of the organization creating the sheet and its date of issue

2. Material's identity, including its chemical and common names

3. Hazardous ingredients

4. Exposure limits

5. Physical and chemical hazards and characteristics

6. Health hazards, including acute and chronic effects

7. Emergency and first aid procedures

8. Spill, leak, and disposal procedures

9. Precautions and safety equipment

 

Exercise:            Use a reference source to find the information requested for each of these chemicals. The Chemical Abstracts Service (CAS) maintains a registry of known compounds and gives each compound a unique number akin to a social security number, the CAS number. Reference sources that can be very helpful are:

  1. MSDS sheets.
  2. The label of the bottle.
  3. The Chemfinder web site (http://www.chemfinder.com/
  4. The Merck Index.

            From the MSDS accompanying the reagent you can find its physical data (mp, bp, density), first aid instructions, spill recommendations, and hazard data (TWA, LD50).   The format for MSDS's vary between chemical suppliers. 

            From the label you can record the name of the chemical, its manufacturer, chemical formula, formula weight, catalog number, its ratings of health risks, toxicity, flammability, and corrosiveness, appropriate protective equipment, and any other special warnings listed on the bottle.  There is no uniform labeling system concerning chemicals but chemical manufacturers attempt to display as much pertinent information as possible on their products.   For example the J.T. Baker company rates chemical hazards on a scale of 0‑4 in terms of health (having dangerous or toxic effects if inhaled, ingested, or absorbed), flammability (tendency to burn), reactivity (potential to explode or to react violently when exposed to air, water, or other substances), and corrosiveness (presents danger when exposed to skin, eyes, or mucous membranes) with 0 ‑ no hazard, 1 ‑ slight hazard, 2 ‑ moderate hazard, 3 ‑ severe hazard, 4 ‑ extreme hazard.

            From the Chemfinder web site you can find structures, physical information and MSDS sheets.

            From the Merck Index you can find information on usage and toxicity.

           

Health Hazards

            Toxic chemicals are often categorized as follows: poisons (cause toxic effects), carcinogens (cause cancer), mutagens (cause mutations in DNA), teratogens (cause birth defects), and radioactive (spontaneously emit ionizing radiation).  Toxicity is reported in terms of dosage such as the LD50, the # mg of chemical/kg of body weight that is lethal to 50 % of a given population.  Other parameters include TWA (Time Weighted Average) or  TLV (Threshold Limit Value), and PEL (Permissible Exposure Limit).

            Chemicals can enter the body by a variety of routes: inhalation of gases, vapors, and particulate matter; eye contact; skin contact/absorption; and ingestion via eating, drinking, smoking, biting fingernails, or licking fingers to turn a page.  The use of gloves is required whenever handling chemicals.  Personal hygiene in the lab and after the lab is important.  It is best to have as much of your body covered as possible.  Wear safety glasses at all times!   Gloves and aprons are worn in lab. Limit exposure and contact with chemicals to a maximum.  "An ounce of prevention is worth a pound of cure".  Wash your hands thoroughly immediately after leaving lab.  Spills on hands and skin during lab should be rinsed immediately with water and your instructor should be notified.

 

Use the Resources above to find the following about these two compounds:

p-toluidine(formula =                                )

Stearic Acid(formula =                         )

 

 

 

Structure:

 

 

 

Structure:

Melting point:

Melting point:

Boiling point:

Boiling point:

LD50

LD50

Notes on safe handling:

Notes on safe handling: