safety-in-academic-chemistry-laboratories-students

Note that use of most respirators requires training

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Unformatted text preview: rotection. If the material should be handled in a laboratory hood, in a glovebox, or with extra ventilation, that recommendation might be stated under this heading. (Note that use of most respirators requires training and an examination by a physician.) Fire and explosion hazard data. The information in this section usually includes the following: Flash point. The lowest temperature at which the vapor of the chemical can be ignited by a flame when the chemical is slowly heated in a special apparatus. Several methods exist to establish the flash point; the method used should be specified but often is not. Autoignition temperature. The lowest temperature at which a chemical ignites spontaneously in the air. Flammable limits. All volatile flammable chemicals have minimum and maximum vapor concentrations in air below and above which they cannot be ignited. 13 students short index 1/15/03 12:45 PM Page 14 Flammable limits are approximate values6 expressed as percentage by volume in air, usually at atmospheric pressure and ambient temperature. Note that as the temperature increases, the lower flammable limit decreases and the upper flammable limit increases; increases in pressure also cause a decrease in the lower flammable limit and an increase in the upper flammable limit. Recommended extinguishing media. Some chemicals that are on fire (e.g., magnesium) will burn even more vigorously if water or carbon dioxide is used in an attempt to extinguish the fire. First aid. Describes the procedures for emergency first aid. Be sure you can perform the first aid properly; otherwise, move away so a qualified person can provide the necessary help. Meanwhile, you can summon the ambulance, if necessary. Health hazard data. This includes one or more of the following: LD50 (lethal dose fifty). This is the lethal single dose (usually by ingestion) in milligrams of chemical per kilogram (mg/kg) of animal body weight of a chemical that is expected to kill 50% of a test animal population within a specified time. LC50 (lethal concentration fifty). This is the concentration of a chemical in air expressed as ppm for gases and vapors or...
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