Science and Technology and Engineering: Basics of Safety and Equipment

Laboratory Accidents
Any spills or accidents should be reported to the teacher so that the teacher can determine the safest clean-up method. The student should start to wash off a chemical spilled on the skin while reporting the incident. Some spills may require removal of contaminated clothing and use of the safety shower. Broken glass should be disposed of in a designated container. If someone's clothing catches fire they should walk to the safety shower and use it to extinguish the flames. A fire blanket may be used to smother a lab fire. A fire extinguisher, phone, spill neutralizers, and a first aid box are other types of safety equipment found in the lab. Students should be familiar with routes out of the room and the building in case of fire. Students should use the eye wash station if a chemical gets in the eyes.

Safety Procedures
Students should wear a lab apron and safety goggles. Loose or dangling clothing and jewelry, necklaces, and earrings should not be worn. Those with long hair should tie it back. Care should always be taken not to splash chemicals. Open-toed shoes such as sandals and flip-flops should not be worn, nor should wrist watches. Glasses are preferable to contact lenses since the latter carries a risk of chemicals getting caught between the lens and the eye. Students should always be supervised. The area where the experiment is taking place and the surrounding floor should be free of clutter. Only the lab book and the items necessary for the experiment should be present. Smoking, eating, and chewing gum are not permitted in the lab.
Cords should not be allowed to dangle from work stations. There should be no rough-housing in the lab. Hands should be washed after the lab is complete.

Fume Hoods
Because of the potential safety hazards associated with chemistry lab experiments, such as fire from vapors and the inhalation of toxic fumes, a fume hood should be used in many instances. A fume hood carries away vapors from reagents or reactions. Equipment or reactions are placed as far back in the hood as practical to help enhance the collection of the fumes.
The glass safety shield automatically closes to the appropriate height, and should be low enough to protect the face and body. The safety shield should only be raised to move equipment in and out of the hood. One should not climb inside a hood or stick one's head inside. All spills should be wiped up immediately and the glass should be cleaned if a splash occurs.

Common Safety Hazards
Some specific safety hazards possible in a chemistry lab include:
Fire: Fire can be caused by volatile solvents such as ether, acetone, and benzene being kept in an open beaker or Erlenmeyer flask.
Vapors can creep along the table and ignite if they reach a flame or spark.
Solvents should be heated in a hood with a steam bath, not on a hot plate.
Explosion: Heating or creating a reaction in a closed system can cause an explosion, resulting in flying glass and chemical splashes.
The system should be vented to prevent this.
Chemical and thermal burns: Many chemicals are corrosive to the skin and eyes.
Inhalation of toxic fumes: Some compounds severely irritate membranes in the eyes, nose, throat, and lungs.
Absorption of toxic chemicals such as dimethyl sulfoxide (DMSO) and nitrobenzene through the skin.
Ingestion of toxic chemicals.

Safety Gloves
There are many types of gloves available to help protect the skin from cuts, burns, and chemical splashes. There are many considerations to take into account when choosing a glove. For example, gloves that are highly protective may limit dexterity. Some gloves may not offer appropriate protection against a specific chemical. Other considerations include degradation rating, which indicates how effective a glove is when exposed to chemicals; breakthrough time, which indicates how quickly a chemical can break through the surface of the glove; and permeation rate, which indicates how quickly chemicals seep through after the initial breakthrough.
Disposable latex, vinyl, or nitrile gloves are usually appropriate for most circumstances, and offer protection from incidental splashes and contact. Other types of gloves include butyl, neoprene, PVC, PVA, viton, silver shield, and natural rubber. Each offers its own type of protection, but may have drawbacks as well. Double-gloving can improve resistance or dexterity in some instances.

Proper Handling and Storage of Chemicals
Students should take care when carrying chemicals from one place to another. Chemicals should never be taken from the room, tasted, or touched with bare hands. Safety gloves should be worn when appropriate and glove/chemical interactions and glove deterioration should be considered. Hands should always be washed thoroughly after a lab.
Potentially hazardous materials intended for use in chemistry, biology, or other science labs should be secured in a safe area where relevant Safety
Data Sheets (SDS) can be accessed. Chemicals and solutions should be used as directed and labels should be read before handling solutions and chemicals.
Extra chemicals should not be returned to their original containers, but should be disposed of as directed by the school district's rules or local ordinances.
Local municipalities often have hazardous waste disposal programs. Acids should be stored separately from other chemicals. Flammable liquids should be stored away from acids, bases, and oxidizers.

Bunsen Burners
When using a Bunsen burner, loose clothing should be tucked in, long hair should be tied back, and safety goggles and aprons should be worn. Students should know what to do in case of a fire or accident. When lighting the burner, strikers should always be used instead of matches. Do not touch the hot barrel. Tongs (never fingers) should be used to hold the material in the flame. To heat liquid, a flask may be set upon wire gauze on a tripod and secured with an iron ring or clamp on a stand. The flame is extinguished by turning off the gas at the source.

Safety Procedures Related to Animals
Animals to be used for dissections should be obtained from a company that provides animals for this purpose. Road kill or decaying animals that a student brings in should not be used. It is possible that such an animal may have a pathogen or a virus, such as rabies, which can be transmitted via the saliva of even a dead animal. Students should use gloves and should not participate if they have open sores or moral objections to dissections. It is generally accepted that biological experiments may be performed on lower-order life forms and invertebrates, but not on mammalian vertebrates and birds. No animals should be harmed physiologically. Experimental animals should be kept, cared for, and handled in a safe manner and with compassion. Pathogenic (anything able to cause a disease) substances should not be used in lab experiments.

Lab Notebooks
A lab notebook is a record of all pre-lab work and lab work. It differs from a lab report, which is prepared after lab work is completed. A lab notebook is a formal record of lab preparations and what was done. Observational recordings should not be altered, erased, or whited-out to make corrections. Drawing a single line through an entry is sufficient to make changes. Pages should be numbered and should not be torn out. Entries should be made neatly, but don't necessarily have to be complete sentences. Entries should provide detailed information and be recorded in such a way that another person could use them to replicate the experiment. Quantitative data may be recorded in tabular form, and may include calculations made during an experiment. Lab book entries can also include references and research performed before the experiment. Entries may also consist of information about a lab experiment, including the objective or purpose, the procedures, data collected, and the results.

Lab Reports
A lab report is an item developed after an experiment that is intended to present the results of a lab experiment. Generally, it should be prepared using a word processor, not hand-written or recorded in a notebook. A lab report should be formally presented. It is intended to persuade others to accept or reject a hypothesis. It should include a brief but descriptive title and an abstract. The abstract is a summary of the report. It should include a purpose that states the problem that was explored or the question that was answered. It should also include a hypothesis that describes the anticipated results of the experiment. The experiment should include a control and one variable to ensure that the results can be interpreted correctly. Observations and results can be presented using written narratives, tables, graphs, and illustrations. The report should also include a summation or conclusion explaining whether the results supported the hypothesis.

Types of Laboratory Glassware
Two types of flasks are Erlenmeyer flasks and volumetric flasks. Volumetric flasks are used to accurately prepare a specific volume and concentration of solution. Erlenmeyer flasks can be used for mixing, transporting, and reacting, but are not appropriate for accurate measurements.
A pipette can be used to accurately measure small amounts of liquid. Liquid is drawn into the pipette through a bulb. The liquid measurement is read at the meniscus. There are also plastic disposable pipettes. A repipette is a hand-operated pump that dispenses solutions.
Beakers can be used to measure mass or dissolve a solvent into a solute. They do not measure volume as accurately as a volumetric flask, pipette, graduated cylinder, or burette.
Graduated cylinders are used for precise measurements and are considered more accurate than Erlenmeyer flasks or beakers. To read a graduated cylinder, it should be placed on a flat surface and read at eye level. The surface of a liquid in a graduated cylinder forms a lens-shaped curve.
The measurement should be taken from the bottom of the curve. A ring may be placed at the top of tall, narrow cylinders to help avoid breakage if they are tipped over.
A burette, or buret, is a piece of lab glassware used to accurately dispense liquid. It looks similar to a narrow graduated cylinder, but includes a stopcock and tip. It may be filled with a funnel or pipette.

Microscopes
There are different kinds of microscopes, but optical or light microscopes are the most commonly used in lab settings. Light and lenses are used to magnify and view samples. A specimen or sample is placed on a slide and the slide is placed on a stage with a hole in it. Light passes through the hole and illuminates the sample. The sample is magnified by lenses and viewed through the eyepiece. A simple microscope has one lens, while a typical compound microscope has three lenses. The light source can be room light redirected by a mirror or the microscope can have its own independent light source that passes through a condenser. In this case, there are diaphragms and filters to allow light intensity to be controlled. Optical microscopes also have coarse and fine adjustment knobs.
Other types of microscopes include digital microscopes, which use a camera and a monitor to allow viewing of the sample. Scanning electron microscopes (SEMs) provide greater detail of a sample in terms of the surface topography and can produce magnifications much greater than those possible with optical microscopes. The technology of an SEM is quite different from an optical microscope in that it does not rely on lenses to magnify objects, but uses samples placed in a chamber. In one type of SEM, a beam of electrons from an electron gun scans and actually interacts with the sample to produce an image.
Wet mount slides designed for use with a light microscope typically require a thin portion of the specimen to be placed on a standard glass slide. A drop of water is added and a cover slip or cover glass is placed on top. Air bubbles and fingerprints can make viewing difficult.
Placing the cover slip at a 45-degree angle and allowing it to drop into place can help avoid the problem of air bubbles. A cover slip should always be used when viewing wet mount slides. The viewer should start with the objective in its lowest position and then fine focus. The microscope should be carried with two hands and stored with the low-power objective in the down position. Lenses should be cleaned with lens paper only. A graticule slide is marked with a grid line, and is useful for counting or estimating a quantity.

Balances
Balances such as triple-beam balances, spring balances, and electronic balances measure mass and force. An electronic balance is the most accurate, followed by a triple-beam balance and then a spring balance. One part of a triple-beam balance is the plate, which is where the item to be weighed is placed. There are also three beams that have hatch marks indicating amounts and hold the weights that rest in the notches. The front beam measures weights between 0 and 10 grams, the middle beam measures weights in 100 gram increments, and the far beam measures weights in 10 gram increments. The sum of the weight of each beam is the total weight of the object. A triple beam balance also includes a set screw to calibrate the equipment and a mark indicating the object and counterweights are in balance.

Chromatography
Chromatography refers to a set of laboratory techniques used to separate or analyze mixtures.
Mixtures are dissolved in their mobile phases. In the stationary or bonded phase, the desired component is separated from other molecules in the mixture.
In chromatography, the analyte is the substance to be separated. Preparative chromatography refers to the type of chromatography that involves purifying a substance for further use rather than further analysis. Analytical chromatography involves analyzing the isolated substance. Other types of chromatography include column, planar, paper, thin layer, displacement, supercritical fluid, affinity, ion exchange, and size exclusion chromatography.
Reversed phase, two-dimensional, simulated moving bed, pyrolysis, fast protein, counter current, and chiral are also types of chromatography. Gas chromatography refers to the separation technique in which the mobile phase of a substance is in gas form.

Reagents and Reactants
A reagent or reactant is a chemical agent for use in chemical reactions. When preparing for a lab, it should be confirmed that glassware and other equipment has been cleaned and/or sterilized. There should be enough materials, reagents, or other solutions needed for the lab for every group of students completing the experiment. Distilled water should be used instead of tap water when performing lab experiments because distilled water has most of its impurities removed. Other needed apparatus such as funnels, filter paper, balances, Bunsen burners, ring stands, and/or microscopes should also be set up. After the lab, it should be confirmed that sinks, workstations, and any equipment used have been cleaned. If chemicals or specimens need to be kept at a certain temperature by refrigerating them or using another storage method, the temperature should be checked periodically to ensure the sample does not spoil.

Diluting Acids
When preparing a solution of dilute acid, always add the concentrated acid solution to water, not water to concentrated acid. Start by adding ~2/3 of the total volume of water to the graduated cylinder or volumetric flask. Next, add the concentrated acid to the water. Add additional water to the diluted acid to bring the solution to the final desired volume.

Cleaning After Acid Spills
In the event of an acid spill, any clothes that have come into contact with the acid should be removed and any skin contacted with acid must be rinsed with clean water. To the extent a window can be opened or a fume hood can be turned on, do so. Do not try force circulation, such as by adding a fan, as acid fumes can be harmful if spread.
Next, pour one of the following over the spill area: sodium bicarbonate, baking soda, soda ash, or cat litter. Start from the outside of the spill and then move towards the center, in order to prevent splashing. When the clumps have thoroughly dried, sweep up the clumps and dispose of them as chemical waste.

Centrifuges
A centrifuge is used to separate the components of a heterogeneous mixture (consisting of two or more compounds) by spinning it. The solid precipitate settles in the bottom of the container and the liquid component of the solution, called the centrifugate, is at the top. A well-known application of this process is using a centrifuge to separate blood cells and plasma. The heavier cells settle on the bottom of the test tube and the lighter plasma stays on top. Another example is using a salad spinner to help dry lettuce.

Electrophoresis, Calorimetry, and Titration
Electrophoresis is the separation of molecules based on electrical charge. This is possible because particles disbursed in a fluid usually carry electric charges on their surfaces. Molecules are pulled through the fluid toward the positive end if the molecules have a negative charge and are pulled through the fluid toward the negative end if the molecules have a positive charge.
Calorimetry is used to determine the heat released or absorbed in a chemical reaction.
Titration helps determine the precise endpoint of a reaction. With this information, the precise quantity of reactant in the titration flask can be determined. A burette is used to deliver the second reactant to the flask and an indicator or pH meter is used to detect the endpoint of the reaction.

Field Studies and Research Projects
Field studies may facilitate scientific inquiry in a manner similar to indoor lab experiments. Field studies can be interdisciplinary in nature and can help students learn and apply scientific concepts and processes. Research projects can be conducted in any number of locations, including school campuses, local parks, national parks, beaches, or mountains. Students can practice the general techniques of observation, data collection, collaborative planning, and analysis of experiments. Field studies give students the chance to learn through hands-on applications of scientific processes, such as map making in geography, observation of stratification in geology, observation of life cycles of plants and animals, and analysis of water quality.
Students should watch out for obvious outdoor hazards.
These include poisonous flora and fauna such as poison ivy, poison oak, and sumac.
Depending on the region of the United States in which the field study is being conducted, hazards may also include rattlesnakes and black widow or brown recluse spiders. Students should also be made aware of potentially hazardous situations specific to geographic locales and the possibility of coming into contact with pathogens.
Field studies allow for great flexibility in the use of traditional and technological methods for making observations and collecting data. For example, a nature study could consist of a simple survey of bird species within a given area. Information could be recorded using still photography or a video camera. This type of activity gives students the chance to use technologies other than computers. Computers could still be used to create a slide show of transferred images or a digital lab report. If a quantitative study of birds was being performed, the simple technique of using a pencil and paper to tabulate the number of birds counted in the field could also be used. Other techniques used during field studies could include collecting specimens for lab study, observing coastal ecosystems and tides, and collecting weather data such as temperature, precipitation amounts, and air pressure in a particular locale.