Safety in the Laboratory, Chemistry tutorial

Introduction:

Organic chemistry is an experimental science. Our understanding of this aspect of chemistry is mainly the consequence of laboratory observation and testing. For this cause, the laboratory is a significant ingredient of a student's tutoring in organic chemistry.

Since of the nature of organic compounds, the organic chemistry laboratory is usually more hazardous than the inorganic chemistry laboratory. Many organic compounds are volatile and flammable. Several can source chemical burns; many are toxic. Various can because lung damage, several can guide to cirrhosis of the liver, and some are carcinogenic (causing cancer). Yet, organic chemists normally live as long as the rest of the population because they contain learned to be careful. Whenever working in an organic laboratory, we must always believe in terms of safety.

Personal safety:

Using Common Sense

Most laboratory safety measures are nothing more than common sense. The laboratory is not a place for horseplay. Don't work alone in the laboratory. Never perform unauthorized experiments. Never sniff, inhale, touch or taste organic compounds, and do not pipette them via mouth. Wipe acids and bases. Neutralize residual spilled acid through sodium bicarbonate and spilled base by dilute acetic acid. Don't put hazardous chemicals in the waste crock - the janitor may become injured. Never pour chemicals down the sink - the atmosphere will be injured. Instead, utilize the containers gives for chemical disposal.

Whenever working in the laboratory, bear appropriate clothing. Jeans and a shirt will rolled-up sleeves, plus a rubber lab apron or cloth lab coat, are ideal. Never wear your best clothing -laboratory apparel generally acquires many small holes from acid splatters and might as well develop a distinctive aroma. Loose sleeves can sweep flasks from the laboratory bench, and they present the adjoined danger of easily catching on fire. Long hair should be tied back. Broken glass at times litters the floor of a laboratory; hence, always wear shoes. Sandals are inadequate since they don't protect the feet from spills. Wash your hands regularly, and always wash them before leaving the laboratory, even to go to the rest room. Because of the danger of fires, smoking is prohibited in laboratories.

Since of the danger of chemical contamination as well, food and drink too contain no place in the laboratory. On the 1st day of class, familiarize manually through the locations of the fire extinguishers, fire blanket, eyewash fountain and shower.

Safety glasses

Chemicals splashed in the eyes can lead to blindness; hence it is imperative that we bear safety glasses, or better, safety goggles. Wear them at all times, even if we are merely adding notes to your laboratory notebook or washing dishes. You could be an innocent victim of your lab partner's mistake, who might inadvertently splash a corrosive chemical in your direction. In the case of particularly hazardous manipulations, you should wear a full-face shield (similar to a welder's face shield).Your instructor will tell you when this is necessary.

Contact lenses shouldn't be worn, even under safety glasses. The reason for this rule is that contact lenses cannot always be removed rapidly if a chemical gets into your eye. A person administering 1st aid via washing your eye might not even realize that we are wearing contact lenses. In addition, "soft" contact lenses can absorb harmful vapours. If contact lenses are absolutely needed, properly fitted goggles must be worn. As well inform our laboratory instructor and neighbors that we are wearing contact lenses.

Laboratory accidents:

Chemicals in the Eyes

If a chemical does get into our eye, flush it with gently flowing water for 15 minutes. Don't try to neutralize an acid or base in the eye. Since of the natural tendency of the eyelids to shut when something is in the eye, they must be held upon during the washing. If there is no eyewash fountain in the laboratory, a piece of rubber tubing attached to a tap is a good substitute. Don't take time to put together a fountain if we have something in our eye, though either splash your eye (held open) with water from the tap immediately or lie down on the floor and have someone pour a gentle stream of water into our eye. Time is vital. The sooner we can wash a chemical out of our eye, the less the harm will be.

After the eye has been flushed, medical treatment is powerfully advised. For any corrosive chemical, these as sodium hydroxide, prompt medical attention is imperative.

Chemical burns

Any chemical (whether water-soluble or not) spilled onto the skin should be rinsed off instantly via soap and water. The detergent action of the soap and the mechanical action of washing remove most substances, even insoluble ones. If the chemical is a strong acid or base, clean the splashed area of the skin by lots and lots of cool water. Strong acids on the skin generally cause a painful stinging. Strong bases usually don't cause pain, but they are very harmful to tissue. Always rinse watchfully after using a strong base.

If chemicals are spilled on a large area of the body, wash them off in the safety shower. If the chemicals are corrosive or can be absorbed through the skin, eliminate contaminated clothing so that the skin can be flushed thoroughly. If chemical burns consequence, the victim should seek medical attention.

Heat burns

Minor burns from hot flasks, hot tubing, and the likes are not uncommon occurrences in the laboratory. The only treatment needed for a very minor burn is holding it under cold water for 5 -10 minutes. A painkilling lotion might then be applied. To prevent minor burns, keep a pair of inexpensive loose-fitting cotton gloves in our laboratory locker to utilize whenever we must handle hot beakers, tubing or flasks.

A person through a serious burn, as from burned clothing, is likely to go into shock. He or she should be made to lie down on the floor and kept warm by the fire blanket or through a coat. Then, an ambulance should be termed. Except to extinguish flames or to take away harmful chemicals, don't wash a serious burn and don't apply any ointment. Though, cold compresses on a burned area will help dissipate heat.

Cuts

Minor cuts from broken glassware are another general occurrence in the laboratory. These cuts should be flushed thoroughly through cold water to remove any chemicals or sliver of glass. A pressure bandage can be utilized to stop any bleeding.

Major cuts and heavy bleeding are a more serious matter. The injured person should lie down and be kept warm in case of shock. A pressure bandage (such as folded, clean dish towel) should be applied over the wound and the injured area elevated slightly, if possible. An ambulance should be termed instantly.

Inhalation of Toxic Substances

A person who has inhaled vapours of an irritating or toxic substance should be taken away immediately to fresh air. If breathing stops, artificial respiration should be administered and an emergency medical vehicle called.

Laboratory fires:

Avoiding fires

Most fires in the laboratory can be avoided via the employ of common sense. Before lighting a match or burner, check the area for flammable solvents. Solvent fumes are heavier than air and can pass through along a bench top or drainage through in the bench. Such heavy flammable fumes can remain in sinks or waste baskets for days. While it is indeed true that a flammable solvent shouldn't have been discarded in the sink or waste basket, it is for eternity possible that several inconsiderate mates or colleagues contain done so. Hence, don't discard hot matches, even if extinguished, or any other hot material in sinks or waste baskets.

Whenever we utilize a flammable solvent, extinguish all flames in the vicinity beforehand. For eternity cap solvent bottles whenever not actually in utilize. Never boil away flammable solvents from a mixture except in the fume hood. Situate solvent-soaked filter paper in the fume hood to dry before rejecting it in a waste container. Spilled solvent shouldn't be allowed simply to evaporate. If a solvent is spilled, clean it up instantly through paper towels that should be situated in the hood to dry.

Solvents should never be poured into a drainage trough (that is for water only). Since of ecological concerns, solvents should be disposed of only in containers provided for solvent disposal. In general, such disposal containers are placed in the fume hood in the laboratory.

Extinguishing fires

In case of even a small fire, tell our neighbours to relinquish the area and inform the instructor. A fire detained to a flask or beaker can be smothered through a watch glass of large beaker situated over the flaming vessel. (Try not to drop a flaming flask - this will splatter burning liquid and glass over the area). All burners in the vicinity of a fire should be extinguished, and all containers of flammable materials should be eliminated to a safe place in case the fire extends.

For every but the smallest fire, the laboratory should be cleared of people. It is better to say noisily, 'Clear the room', than to scream 'Fire' in a panicky voice. If we hear these shout, don't stand around to see what is happening, but stop whatever we are doing and walk instantaneously and purposefully toward the nearest clear exit.

Many organic solvents float in water; hence water may serve only to extend a chemical fire. Several substances, as sodium metal, explode on contact through water. For such causes, water shouldn't be out to extinguish a laboratory fire; instead, a carbon dioxide or powdered fire extinguisher should be utilized.

If a fire extinguisher is needed, it is best to clear the laboratory and allow the instructor to handle the extinguisher. Even so, you should acquaint yourself with the location, classification and operation of the fire extinguish the first day of class. Inspect the fire extinguishers. Find the sealing wire (indicating that the extinguisher is fully charged) and the pin that is utilized to break this sealing wire whenever the extinguisher is required.

Fire extinguishers usually spray their contents through great force. To avoid blowing flaming liquid and broken glass around the room, aim toward the base and to the side of any burning equipment, not directly toward the fire. Once a fire extinguisher has been employed, it will need recharging before it is again operable. Hence, any employ of a fire extinguisher must be reported to the instructor.

Extinguishing burning clothing

If our clothing catches fire, walk (don't run) to the shower, if it is close via. If the shower isn't near, lie down, roll to extinguish the flames, and call for assist.

A clothing fire might be extinguished via having the person roll in a fire blanket. The rolling motion is vital since fire can still burn under the blanket. Wet towels can be utilized to extinguish burning clothing. A burned person should be treated for shock (kept quiet and warm). Medical consideration should be sought.

Handling chemicals:

Acids and Bases

To prevent acid splatters, always adjoin concentrated acids to water (never add water to acids). Concentrated sulphuric acid (H2SO4) should be added to ice water or crushed ice since of the heat produced via the mixing. Don't pour acids down the drain with no first diluting them (through adding to large amounts of water) and then neutralizing them. Strong bases should as well be diluted and discarding. If we splash an acid or strong base on our skin, wash by plentiful amounts of water, as described in the section on chemical burns. Concentrated hydrochloric acid (HCl) and glacial acetic acid (CH3COOH) present the added hazard of very irritating vapours. Such 2 acids should be employed only in the fume hood.

Sodium hydroxide (NaOH) is caustic and can eat away living tissues. As a solid (generally pellets), it is deliquescent; a pellet which is dropped and ignored will form a hazardous pool of concentrated NaOH. Pick up spilled pellets while wearing plastic gloves or by using a piece of paper, neutralize them, and then flush the neutralized mixture down the drain by large amounts of water.

Aqueous ammonia (ammonium hydroxide, NH4OH) emits ammonia (NH3) vapours and therefore should be utilized only in the fume hood.

Solvents

Organic solvents present the double hazard of flammability and toxicity (both short-term and cumulative). 

  • Diethyl ether (C2H5OC2H5) and petroleum ether (a mixture of alkanes) are both extremely volatile (having low boiling points) and extremely flammable. Such 2 solvents should never be utilized in the vicinity of a flame, and they should be boiled only in the hood.
  • Carbon disulphide (CS2) that is now hardly ever utilized in the organic laboratory is exclusively hazardous. Its ignition temperature is under 100oC, the boiling point of water. Therefore, fires can consequence even from its contact by a steam pipe.
  • Benzene (C6H6) is flammable and as well extremely toxic compound. It can be absorbed through the skin, and long-term exposure is thought to reason cancer. Benzene should be utilized as a solvent only whenever completely needed (and then handled by great care to avoid inhalation, splashes on the skin, or fire). In most cases toluene can be substituted for benzene. Even though toluene is flammable, it is less toxic than benzene.
  • Most halogenated hydrocarbons, such as carbon tetrachloride (CCl4) and chloroform (CHCl3), are toxic, and some are carcinogenic. Halogenated hydrocarbons tend to accumulate in the fatty tissues of living systems, instead of being detoxified and excreted, as most poisons. In repeated small doses, they are associated with chronic poisoning and damage to the liver and kidneys. If either carbon tetrachloride or chloroform must be used, it should be handled in the fume hood.

Since of the dangers inherent by every organic solvent, they should always be handled through respect. Solvent vapours shouldn't be inhaled, and solvents should never be tasted or poured on the skin. Wash any splashes on our skin immediately by soap and water. Keep solvent bottles tightly capped. Always observe preventative measures to avoid fires.

Symbols used to convey Information about Chemicals

Below are some of the symbols used to convey information about chemicals:

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