Write techniques of handling chemicals. Write techniques for pouring and transferring liquids.

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 Laboratory Rules and Safety

Chemistry wet laboratories contain certain inherent dangers and hazards. As a chemistry student working in a laboratory, you must learn how to work safely with these hazards in order to prevent injury to yourself and others around you. You must make a constant effort to think about the potential hazards associated with what you are doing, and to think about how to work safely to prevent or minimize these hazards as much as possible. The following guidelines are here to help you. Please understand and follow these guidelines and act according to the principles behind them to help everybody to be as safe as possible. Ultimately, your own safety is your own responsibility. Please make sure you are familiar with the safety precautions, hazard warnings and procedures of the experiment you are performing on a given day before you start any work. If you are unsure of how to do something safely, please ask the TA before proceeding. Experiments should not be performed without an instructor in attendance and must not be left unattended while in progress. No unauthorized experiments are allowed. No modification of the experiments is allowed. No work outside of regular hours is allowed, except under exceptional circumstances. 

Anyone who fails to be governed by the Safety Regulations is subject to disciplinary action and possible removal from the laboratory and course.

Safety Rules

Make sure you are familiar with all the safety information given to you about each experiment before starting the experiment. This includes your manual, these safety guidelines, any posted information or any other information provided to by your TA.

Always wear safety glasses (including during check-in and check-out), except when their removal has been specifically authorized by the TA prior to their removal. Contact lenses are forbidden. You must also wear a face shield when requested to by the TA.

You must wear a lab coat (and do it up) in all Chemistry labs.

Footwear must completely cover the foot and heel (no sandals, baby dolls, ballet flats, mules, open-toed footwear, etc.).

You must wear long pants (no shorts, capris, skirts, or dresses).

If you arrive at your Chemistry lab and do not have the required clothing, you will be directed to rent or purchase missing items (glasses, lab coats, disposable foot coverings and long pants) from Chemistry Stores before you will be allowed to participate in the lab.

Loose hair must be tied back so as to be out of the way. Dangling jewellery must be removed. Do not eat or drink in the lab.

Visitors are not allowed to be in the lab.

1. Please keep your work area and the common work areas tidy. Also, please make sure the aisles, safety showers, eyewash stations and doorways are unobstructed.
2.  Please leave all glassware, equipment, tools, etc. as clean or cleaner than you found them.
3.  Please clean up spills immediately. If the spill is large or is of a hazardous material, inform the TA immediately. Use spill mix to absorb solvent or caustic liquids.
4. Please dispose of waste properly and in a timely manner and according to the instructions provided in your lab manual. If you are not sure, please ask your TA for the proper method of disposal.
5. Wash your hands before you leave the lab.
6. Do not remove chemicals or equipment from the lab except when required to do so for analysis.
7. Please notify your TA of any serious medical conditions.
8. Do not wear earbuds or earphones while in the lab.

The vapours of many organic solvents are flammable or combustible. Do not expose electric sparks, open flames and heating elements to organic solvent vapours. UNLESS OTHERWISE STATED, ASSUME ALL ORGANIC SOLVENTS ARE FLAMMABLE.

Many chemicals (solid, liquid or vapour) are poisonous. Do not taste chemicals. If it is necessary to smell a chemical, do so by fanning the vapours towards your nose. Never inhale directly. Avoid inhaling dust or fine powders. Use fume hoods and personal protective equipment when necessary.

Do not pipet with your mouth. .

Managing Reagent Chemicals

1. Selecting Reagent Chemicals

Each school system should develop a list of reagents acceptable for use in the various science courses. A teacher who wishes to use a substance not on the appropriate list must seek the permission of the science supervisor by submitting a written request. The request should include the following:

• A copy of the lesson plan for the proposed demonstration or laboratory exercise.
• Information supporting the following assertions:
• Use of the substance is pedagogically sound.
• The demonstration or laboratory exercise using the substance is an effective way to illustrate an important property, process or concept.
• No satisfactory substitute for the substance is readily available.
• Adequate safeguards are in place to ensure proper use of the substance.
• Students will be instructed in the proper handling of the substance (as indicated in the lesson plan).
• Information on the following to enable the supervisor to make an informed decision:
• the extent of exposure of students and the teacher to the chemical (including estimate of time to the nearest minute).
• the age or maturity level of the students who will be exposed.
• In considering a substance for use in the laboratory, teachers are advised to check hazardous materials lists available in print and on the Internet. Resources available include the following:

The National Toxicological Program for lists of carcinogenic and reproductive toxins (teratogens and mutagens)

The National Research Council’s Prudent Practices in the Laboratory (1995), Chapter 3, for lists of carcinogens, mutagens, teratogens, and highly flammable materials

• The Oak Ridge Toxicology Information Resources Center’s Catalog of Teratogenic Agents
• Appearance of a substance on one of these lists does not preclude its appropriate use in the school laboratory. The dose makes the difference. Even common substances such as water and salt can be toxic in excessive quantities. Many substances that are toxic at some levels can safely be used at lower levels.
• Materials Safety Data Sheets (MSDSs), which provide information on toxicity levels, may be found on the Internet.
• Chemical Inventory: Inventories of reagents are essential in the control of chemical hazards. They enable members of the science department to determine the existence of a specific reagent chemical, its location, and its approximate shelf age. A reagent chemical inventory should be conducted at least once a year. The chemical inventory record should 
• contain the date the inventory was conducted.
• identify chemical reagents by name and formula.
• specify the amount of each reagent present.
• indicate the storage location of each reagent.
• indicate the hazard of each reagent, using information from the Material Data Safety Sheet (MSDS) for each substance and the appropriate National Fire Protection Association hazard code.

Chemical Storage

. General Guidelines

• Secure storage areas against unauthorized removal of chemicals by students or others.
• Protect the school environment by restricting emissions from stored reagent chemicals. Vents should be ducted to the outside.
• Where possible, storage areas should have two separate exits. 
• Maintain clear access to and from the storage areas.
• Do not store chemicals in aisles or stairwells, on desks or laboratory benches, on floors or in hallways, or in fume hoods.
• Use NFPA- or OSHA-approved storage cabinets for flammable chemicals.
• Use an appropriate “Acid Cabinet” for any acid solutions of 6 M concentration or higher. Nitric acid needs to be isolated.
• Use refrigerators of explosion-proof or explosion-safe design only. Do not use standard refrigerators to store flammable chemicals. Place NO FOOD labels on refrigerators used to store chemicals.
• Label storage areas with a general hazard symbol to identify hazardous chemicals and indicate correct fire fighting procedures.
• See Appendix E, NFPA Hazard Codes.
• File a Material Safety Data Sheet (MSDS) for every chemical stored in the laboratory.
• Store all reagent chemicals in compatible family groups. Do not alphabetize.
• See Appendix F, Storage of Chemicals.
• Store all chemicals at eye level and below. The preferred shelving material is wood treated with polyurethane or a similar impervious material. All shelving should have a two-inch lip. If you use shelving with metal brackets, inspect the clips and brackets annually for corrosion and replace as needed.
• Store chemical reagents prepared in the laboratory in plastic bottles (if possible and appropriate to the chemical) to minimize the risk of breakage.
• Date containers upon receipt and again when opened.
• Attach chemical labels with all necessary information to all containers.
• See Chapter VII.A.5, Labeling of Stored Reagent Chemicals.
• When opening newly received reagent chemicals, immediately read the warning labels to be aware of any special storage precautions such as refrigeration or inert atmosphere storage.
• Test peroxide-forming substances periodically for peroxide levels; dispose of these substances after three months unless the MSDS for the substance indicates a longer shelf life.
• See Appendix G, Hazards of Peroxide-Forming Substances, and Appendix C, Materials Data Safety Sheets (MSDS): Explanation and Samples.
• Check chemical containers periodically for rust, corrosion, and leakage.
• Store bottles of especially hazardous and moisture-absorbing chemicals in chemical-safe bags.
• Maintain a complete inventory in the room where the chemicals are stored, and make a copy available to fire fighters.
• Keep storage areas clean and orderly at all times.
• Have spill cleanup supplies (absorbents, neutralizers) in any room where chemicals are stored or used.

a. Storage of Flammable and Combustible Liquids

Flash point is defined as the minimum temperature of a liquid at which it gives off sufficient vapor to form an ignitable mixture with air.

Flammable liquid is defined as any liquid that has a flash point below 100 F (37.8°C).

Combustible liquid is defined as any liquid that has a flash point at or above 100 F (37.8 ° C).

. Guidelines

• Limit the amount of flammable and combustible materials stored to that required for one year of laboratory work.
• When possible, store flammable and combustible liquids in their original containers or safety cans. A safety can is an approved container of not more than 5 gallons (18.9 L) capacity. The container should have a spring-closed spout cover and an integral flame-arrester and be designed to relieve internal pressure safely when exposed to fire.

b. Storage of Compressed Gases

• Use small lecture-bottle-type gas cylinders only. Store all gas cylinders in an upright position.
• Store gas cylinders in a cool dry place away from corrosive chemicals or fumes.
• Store gas cylinders away from highly flammable substances.
• When cylinders are no longer in use, shut the valves, relieve the pressure in the gas regulators, removed the regulators, and cap the cylinders.
• Label empty gas cylinders EMPTY or MT.
• Store empty gas cylinders separately from full gas cylinders.
• Store flammable or toxic gases at or above ground level – not in basements.
• Use cylinders of toxic, flammable, or reactive gases in fume hoods only.
• When moving cylinders, be sure the valve cap is securely in place to protect the valve stem and valve. Do not use the valve cap as a lifting lug.
• If large gas cylinders are used, they should be chained. A hand truck should be available for transporting them to and from the storage area.

Labeling of Stored Reagent Chemicals

Proper labeling is fundamental to a safe and effective laboratory operation. Reagents created in the laboratory also require labeling.

Purchased Reagent Chemicals

All purchased reagent chemicals should be labeled with –

• chemical name.
• date received.
• date of initial opening.
• shelf-life.
• storage classification location.
• name and address of manufacturer. 

a. Solutions

All reagents created in the laboratory should be labeled with –

• chemical name and formula.
• concentration.
• date prepared.
• name of person who prepared the reagent.
• storage classification.
• hazard warning label (available from a safety supplier).
• reference to original source of chemical (e.g., manufacturer, which jar, etc.).

B. Handling Reagent Chemicals

1. Dispensing Reagent Chemicals

The MSDS for an individual substance should always be consulted before a chemical is used for any reason. It is the best source of information about possible hazards, spill procedures, handling procedures and first aid for any substance.

Teachers are responsible for instructing their students about safe methods for working with chemicals.

a. Safety Guidelines for Dispensing Reagent Chemicals

• Use the smallest amount of the chemical possible in any experiment. Microscale experiments should be considered.

• Consider distributing the amount of chemical for an experiment into vials for each student. This minimizes waste and can save time during the class period.
• Use proper containers for dispensing solids and liquids. Solids should be contained in wide-mouthed bottles and liquids in containers that have drip-proof lips.
• Label all containers properly.
• Never return dispensed chemicals to stock bottle, as it inevitably results in contamination despite your best precautions.

Dispensing Flammable Liquids

When a liquid flows from one container to another, static electricity can build up in one of the containers. If this charge becomes large enough, a spark will be produced between the containers, and a flammable liquid may be ignited. This is particularly a danger when the liquid is stored in a large container and distributed to smaller containers.

Such containers should be bonded and grounded:

• Bonding refers to providing an electrical connection between the two containers. Commonly this is accomplished by attaching a wire, fastening one end each to the two containers.
• Grounding refers to connecting one of the containers (usually the stationary one) to a grounding source such as a metallic water pipe.

Common Hazards

Four categories of hazards commonly found in school laboratories are: corrosives, flammables, oxidizers/reactives, and toxins. In this section, mercury is discussed separately as a special hazard.

Corrosives

Corrosives are materials that can injure body tissue or cause corrosion of metal by direct chemical action. Major classes of corrosive substances are:

• strong acids (e.g., sulfuric, nitric, hydrochloric and hydrofluoric acids)
• strong bases (e.g., sodium hydroxide and potassium hydroxide)
• dehydrating agents (e.g., sulfuric acid, sodium hydroxide, phosphorus pentoxide, and calcium oxide)
• oxidizing agents (e.g., hydrogen peroxide, chlorine, and bromine)

Flammables

Flammable substances have the potential to catch fire readily and burn in air. A flammable liquid itself does not catch fire; it is the vapors produced by the liquid that burn. Important properties of flammable liquids:

• Flash point is the minimum temperature of a liquid at which sufficient vapor is given off to form an ignitable mixture with air.
• Ignition temperature is the minimum temperature required to initiate self-sustained combustion independent of a heat source.

Oxidizers/Reactives

Oxidizers/reactives include chemicals that can explode, violently polymerize, form explosive peroxides, or react violently with water or atmospheric oxygen.

Oxidizers: An oxidizing agent is any material that initiates or promotes combustion in other materials, either by causing fire itself or by releasing oxygen or other combustible gases.

Reactives: Reactives include materials that are pyrophoric (“flammable solids”), are water reactive, form explosive peroxides, or may undergo such reactions as violent polymerization.

Toxins

A toxic substance is one that, even in small amounts, can injure living tissue.

Methods of Toxins Entering the Body:

• Ingestion – Absorption through the digestive tract. This process can occur through eating with contaminated hands or in contaminated areas.
• Absorption – Absorption through the skin often causes dermatitis. Some toxins that are absorbed through the skin or eyes can damage the liver, kidney, or other organs.
• Inhalation – Absorption through the respiratory tract (lungs) through breathing. This process is the most important route in terms of severity.
• Injection – Percutaneous injection of a toxic substance through the skin. This process can occur in the handling of sharp-edged pieces of broken glass apparatus and through misuse of sharp materials such as hypodermic needles.

Mercury

Mercury and its compounds, both organic and inorganic, are health hazards. Metallic mercury has a measurable vapor pressure, and the production of vapor is accentuated by heating the mercury or subdividing as occurs in a spill. Laboratory sources of mercury include, among others, thermometers, manometers (barometers), and batteries. Not only is the vapor harmful, but the metal itself is absorbable through the intact skin.

Mercury and its compounds should never be found in the elementary or middle school. 

i. In high schools, mercury should be used only under special circumstances. Mercury is acceptable in high school only if all four of these criteria are met:

• No substitute is available that will provide the degree of accuracy required for the operation.
• The teacher has obtained prior approval from the science supervisor.
• All persons in the laboratory working with mercury or an instrument containing mercury wear chemical splash safety goggles, full face shields, aprons, and adequate clothing to prevent skin contact.
• Access to mercury or any instrument containing the element is restricted by keeping source and instrument under lock and key except when in use.

Spill Cleanup

General Notes on Chemical Spills

• Spills should be contained, the area cleared of students, and the spill cleaned up immediately.
• Waste from spill cleanup should be disposed of appropriately.
• See Chapter VII.C, Chemical Waste Strategies.
• After floor spill has been thoroughly cleaned up in the appropriate manner, the area should be mopped dry to minimize the risk of slipping and falling.

Spills that Constitute Fire Hazard

• Extinguish all flames immediately.
• Shut down all experiments.
• Vacate the room until the situation has been corrected.

Mercury Spills

Whenever possible, mercury should not be used in school laboratories. If and when it is used, however, there is a chance of a spill occurring.

Each laboratory should therefore be equipped with a specialized, commercially available, mercury-spill kit. Follow the directions found in your kit for cleaning up a mercury spill.

C. Chemical Waste Strategies

All laboratory work with chemicals eventually produces chemical waste. Everyone associated with the science laboratory shares the legal and moral responsibility to minimize the amount of waste produced and to dispose of chemical waste in a way that has the least impact on the environment. Depending on what is contained in the waste, some waste must be professionally incinerated or deposited in designated landfills, while other waste can be neutralized or discharged in normal streams.

1. Minimizing Waste

a. Alternative Substances

Whenever possible, use less toxic substances in place of the more toxic chemicals to minimize the hazards and disposal costs associated with using certain chemicals. The table below contains a list of suggested substitutions for some toxic chemicals.

Toxic Chemical                                              Substitute

Chloroform                                                     Hexanes

Carbon tetrachloride                                       Hexanes

1,4-Dioxane                                                    Tetrahydrofuran

Benzene                                                          Cyclohexane or Toluene

Xylene                                                            Toluene

2-Butanol                                                        1-Butanol

Lead chromate                                                Copper carbonate

p-Dichlorobenzene                                         Naphthalene, Lauric acid, Cetyl alcohol, 

                                                                        1-Octadecanol, Palmitic acid, or Stearic acid

Potassium                                                       Calcium

Dichromate/Sulfuric acid                               Ordinary detergents

Trisodium phosphate                                      Ordinary detergents

Alcoholic potassium hydroxide                     Ordinary detergents

b. Microscale Laboratories

Microscale experiments reduce the amount of material required, therefore reducing the hazards encountered and disposal costs. Many laboratory manuals on the market describe microscale experiments. These should be considered whenever possible to replace “classic” laboratory experiments. 

c. Classroom Demonstrations

Another way to reduce the hazards for students, and reduce the amount of waste generated, is for the teacher to perform classroom demonstrations for the more hazardous experiments rather than have each student carry out the experiment.

d. Coordinate Laboratory Work

When planning laboratory experiments, try to coordinate with co-workers who may be doing the same or similar experiments so that reagents are made up at one time in the building, thus minimizing the amount of “left-over” reagent at the end of the experiment.

2. Waste Storage Prior to Disposal

• All waste should be stored in properly labeled containers. The label should contain the date, type of waste, and any other pertinent information required by the disposal company.
• Waste should be segregated to avoid unwanted reactions and to allow for cost-effective disposal.
• Waste should be stored in closed containers except when additional waste is being added.
• Each school science department should maintain a central, secure waste storage area.

3. Disposing of Waste

Teachers should be aware of the appropriate method of disposal for any chemical used in the school laboratory. When in doubt, refer to the MSDS, a disposal manual, or the source of the chemical. 

a. Classification of Hazardous Waste

The Environmental Protection Agency classifies wastes as:

• Ignitable: has a flash point below 140°C, is an oxidizer, or is an ignitable compressed gas.
• Corrosive: has a pH equal to or below 2.0 or a pH equal to or greater than 12.5.
• Reactive: is reactive with air or water, is explosive, or is cyanide or sulfide.
• Toxic: has certain levels of certain metals, solvents, or pesticides greater than prescribed limits.
• Others: any chemical found in the lists in 40 CFR 261 subpart D.

Classroom Management

• Make disposal options a part of all laboratory instructions for students. For each chemical waste produced, instruct students as to the appropriate disposal, including disposing of the substance in a disposal container or down the drain.
• Place all laboratory waste in a properly labeled container. The label should contain the date and type of waste.
• Immediately following the laboratory activity, place the waste containers in a secure location until the containers can be removed to the central storage area.
• Some chemical wastes may be recycled. Teachers should seek guidance on recycling from local safety officers or other knowledgeable administrative staff.

Drain Disposal

• Before considering drain disposal, be certain that the sewer flows to a wastewater treatment plant and not to a stream or other natural water course. Check with the local waste water treatment plant authority to determine what substances are acceptable for drain disposal.
• Any substance from a laboratory should be flushed with at least 100 times its own volume of tap water.
• Acids and bases should be at least above pH 3 and below pH 8 before being placed in a sanitary drain.
• If both ions of a compound are on the following lists, that compound may be placed in a sanitary drain:

Positive Ions:

• aluminium
• ammonium
• bismuth
• calcium
• copper
• hydrogen
• iron
• lithium
• magnesium
• potassium
• sodium
• strontium
• tin
• titanium
• zinc
• zirconium

Negative Ions:

• borate
• bromide
• carbonate
• chloride
• cyanate
• hydrogen sulfide
• hydroxide
• iodide
• nitrate
• phosphate
• sulfate
• sulfite
• tetraboratex
• thiocynate

• The following organic compounds can go into drain:

• acetic acid
• oxalic acid
• acetone
• pentanols
• butanols
• propanols
• esters with less than 5 carbon
• sodium salts of carboxylic acid
• ethylene glycol
• formic acid
• glyceroal
• sugars
• methanol

• For additional information on drain disposal of substances, see the National Research Council’s Prudent Practices in the Laboratory (1983).
• If in doubt about the proper disposal of a chemical, check with the local safety officer or refer to Flinn or a similar reference.

Compounds Not Suitable for Drain Disposal

For compounds not suitable for drain disposal, label and package the compound and ship by a shipper approved by the U.S. Department of Transportation to a landfill designated by EPA to receive chemical and hazardous waste. Even though packed, shipped, and disposed of by licensed and approved firms, generators of hazardous waste are responsible for the wastes.

Partb: Lab Techniques

When you first set foot inside a chemistry lab, it can be a little overwhelming. There are chemicals in bottles, flame sources, and all kinds of fragile glassware. Learning the proper techniques, and how to use all the equipment can take time, but we all have to start with the basics.

Lab techniques are the processes and practices that are recommended for using the various equipment in the laboratory. In this lesson, we will go over some of the most basic lab techniques you will need to know.

Pouring, Measuring, and Filtering

How To Transfer Chemicals

SOLIDS

It is usually easier to transfer solids to a wide mouthed container such as a beaker. Take a labeled beaker to the reagent shelf where the chemicals are kept. When you take the top off the reagent bottle, don’t lay it down (risks contamination).Many solid chemicals can be easily transferred by tipping the bottle and slowly rotating the bottle back and forth. Don’t tip the bottle up high and let the contents pour out. If a spatula is provided at the reagent bottle, you may use it. Never use your own spatula. Be sure to put the right lid on the right bottle and return the bottle to its place on the shelf.

LIQUID TRANSFER

Take an appropriately sized, labeled beaker to the reagent shelf. The stopper of the reagent bottle should be held during transfer or, if it is flat, placed upside down on the counter. Carefully pour the amount of reagent that you will need, not extra, into the beaker and then close the reagent bottle.Graduated cylinders are unstable so transfer liquids into the labeled beaker first and then pour from the beaker into your graduated cylinder. It is a good idea to make this latter transfer over a sink.