Safety knowledge for chemical experiments

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1. Methods for dealing with common accidents: (1) If skin comes into contact with concentrated sulfuric acid, first wipe away the acid with a dry cloth, then rinse with clean water, and apply a 3–5% NaHCO3 solution. If concentrated alkali solution gets on the skin, rinse it with water and then apply boric acid solution. If acid gets into the eyes accidentally, rinse them immediately with water, blinking while doing so. (2) If a concentrated solution of phenol comes into contact with the skin, it should be rinsed immediately with alcohol. (3) If heavy metal salts such as copper salts or mercury salts are accidentally ingested, drink soy milk, milk, or egg white immediately to detoxify. (4) In the event of a fire involving metallic sodium or potassium, it should be extinguished using sand; water should not be used, nor should CO2 fire extinguishers or CCl4 fire extinguishers. (5) If a burning alcohol lamp is accidentally knocked over in the laboratory, never use water to extinguish it; instead, cover the flame with sand or a large wet cloth. (6) If the thermometer accidentally breaks the mercury bulb, sulfur powder should be used to cover it in order to prevent poisoning from mercury vapor. 2. Safety knowledge for chemical experiment procedures (1) Before lighting flammable gases such as H2, CO, CH4, C2H4, C2H2, etc., their purity should be checked first to prevent explosions caused by the ignition of impure gases. (2) For experiments such as H2 reducing CuO and CO reducing Fe2O3, ventilation should be carried out before heating; the air inside the experimental setup must be removed first before heating is started, to prevent explosions that may occur due to mixing with the air present in the setup. (3) The preparation of toxic gases should be carried out in a fume hood, and the exhaust gases should be absorbed using appropriate reagents to prevent air pollution. (4) In experiments such as the production of ethylene by mixing ethanol with concentrated sulfuric acid, petroleum distillation, and the synthesis of ethyl acetate, broken porcelain pieces should be added to prevent bumping (to avoid violent agitation of the mixture when heated). (5) If gas is produced by heating and collected using the water displacement method, remove the gas delivery tube from the water first before turning off the alcohol lamp, in order to prevent backflow ； For gases that are highly soluble in water (such as HX, etc.), an inverted funnel should be used for exhaust gas absorption. (6) For some special experiments, safety bottles are also required. Flammable, explosive, and toxic chemical reagents in the laboratory should be stored properly by designated personnel, and wastewater and waste liquids must be treated appropriately. For example: Some waste liquids cannot be poured directly into the sewer system to avoid environmental pollution, such as peroxides and organic substances ； Nitrates and sulfuric acid ； Sulfides and acids ； Strongly oxidizing substances, concentrated hydrochloric acid, and flammable materials ； Wastewater containing heavy metal ions, etc. Furthermore, leftover flammable substances such as sodium, potassium, and white phosphorus, as well as oxidizing agents like KMnO4, KClO3, and Na2O2, as well as flammable and volatile organic compounds, should not be discarded carelessly to prevent fires ； Leftover toxic substances must not be discarded carelessly ； If mercury spills on the ground, it should be covered promptly with litharge powder to prevent poisoning from mercury vapor. (7) When diluting concentrated sulfuric acid, it must be slowly poured into water while stirring continuously to prevent the liquid from splashing.