Chem Lab Rev PDF

MODULE 1 CONDUCT INSIDE THE CHEMICAL LABORATORY 1. Do not perform any unauthorized experiments. Never work in the laboratory without the supervision of your laboratory instructor/technician. 2. Smoking, engaging in practical jokes as well as eating in the laboratory is prohibited. 3....

MODULE 1 CONDUCT INSIDE THE CHEMICAL LABORATORY 1. Do not perform any unauthorized experiments. Never work in the laboratory without the supervision of your laboratory instructor/technician. 2. Smoking, engaging in practical jokes as well as eating in the laboratory is prohibited. 3. Avoid wearing jewelry in the laboratory as this can pose multiple safety hazards. 4. If you have a long hair, please tie it back in the laboratory. 5. Wear appropriate personal protective equipment (PPE) such as safety goggles and laboratory gowns. 6. Wear shoes that adequately cover the whole foot; low-heeled shoes with non- slip soles are preferable. Do not wear sandals, open-toed shoes, open backed shoes, or high-heeled shoes in the laboratory. 7. Do not sit on laboratory tables. 8. Avoid distracting or startling persons working in the laboratory. 9. No cell phone or earphone usage in the active portion of the laboratories or during experimental operations. GENERAL LABORATORY WORK PRECAUTIONS 1. Know the locations of laboratory safety showers, eyewash stations and fire extinguishers. 2. Avoid skin and eye contact with all chemicals. 3. Be careful when handling hot glassware and apparatus in the laboratory. Hot glassware looks just like cold glassware. 4. Report immediately any spills, injuries or accidents to your laboratory instructor/technician. 5. Avoid leaving an experiment while it is in progress. 6. Use equipment only for its designated purpose. 7. Turn off all heating apparatus, gas valves, and water faucets when not in use. 8. Do not point the open end of a test tube to anybody while heating. 9. Make sure no flammable solvents are in the surrounding area when lighting a flame. 10.All containers must have appropriate labels. Unlabeled chemical should never be used. 11.Perform work with hazardous chemicals in a properly working fume hood to reduce potential exposures. 12.Never fill a pipette using mouth suction. Always use a pipetting device. 13.Do not use your thumb as a stopper. Swirl gently or put a piece of parafilm over the opening to mix solutions. 14.Handle chemicals, reagents, and stains carefully and follow all warnings. All bottles and containers are labeled as to contents and potential hazards. If, for example, a label says avoid contact with substance and fumes, do so. For potentially hazardous chemicals, information on the hazards, proper handling, and clean-up is provided on Material Safety Data Sheets (MSDS). 15.Do not taste or intentionally sniff chemicals unless it is a part of the experimental procedure. HOUSEKEEPING AND HYGIENE PRACTICES 1. Always keep your working laboratory area clean and orderly, free from unnecessary objects. 2. Keep your hands away from your face, eyes, mouth, and body while using chemicals. 3. Do not apply cosmetics while in the laboratory or storage area. 4. Wash hands after removing gloves, and before leaving the laboratory. 5. Do not pour reagents and chemicals down the sink. Dispose of these only in designated containers. 6. Properly dispose of broken glassware and other sharp objects (e.g., syringe needles) immediately in designated containers. 7. Thoroughly clean your laboratory workspace at the end of the laboratory session. EMERGENCY PROCEDURES 1. Know the location of all the exits in the laboratory and building as well as the location of emergency phone and numbers. 2. Know the location of and know how to operate the following: Fire extinguishers Alarm systems with pull stations Fire blankets Eye washes First-aid kits Safety showers. 3. In case of an emergency or accident, follow the established emergency plan as explained by the laboratory instructor and evacuate the building via the nearest exit. —--------------------------------------------------------------------------------- MODULE 2 There are various glassware, equipment, and other apparatus that need to be handled and/or operated carefully and properly to obtain reliable observations and results. Some of these basic laboratory techniques are proper measurement of mass, volume determination, heating using laboratory burners, transferring of reagents, filtration of mixtures, and glass tubing manipulation. 1. Measurement of Mass Working in the laboratory will often require accurate determination of sample mass. Mass and weight are often used interchangeably but they have different meanings. Mass is the actual amount of material in an object and does not change with the environment in which it is located. weight is a force resulting from the interaction of the mass with the earth’s gravitational field and varies with location. 2. Volume Determination Graduated cylinders, pipettes, burettes, and volumetric flasks are generally used for measuring volumes of liquids. Volumetric flasks and graduated cylinders are graduated to measure the volume of liquids while pipettes and burettes are calibrated to deliver a specific volume of liquids at a specified temperature. In doing volume measurements using graduated cylinder, always place the cylinder on a flat surface and observe the meniscus at eye-level Meniscus is the curve formed at the upper portion of the liquid. A concave meniscus occurs when molecules of liquid are attracted more strongly with the surface of the container (adhesion) while a convex meniscus occurs when the molecules of liquid are more strongly attracted to each other (cohesion). Measuring pipette should be used in conjunction with a rubber bulb to draw up liquid from a container. The bulb is squeezed first then placed at the top opening of the pipette that is dipped through the liquid through its other end. The liquid is drawn up past the desired level, then the rubber bulb is removed then quickly replaced with index finger. The liquid is drained carefully by minimal lifting of the index finger until the desired level on the pipette’s marking. 3. Heating with Laboratory Burners Many experiments in Chemistry laboratory require heating with a laboratory burner which is a metallic open flame gas burner such as Bunsen burner, Tirrill burner and Meker burner Bunsen burner is the most basic of the three and has no needle valve that regulates gas flow. Meanwhile, the Tirrill burner and Meker burner both have a needle valve below to regulate the gas supply. The Meker burner differs in the presence of a screen on the top of the burner that forms many short, small uniform blue flames cones with a higher temperature. It is therefore more suited for glass blowing and other heating operations that require higher temperature. The principles of operation of different laboratory burners are the same as gas stove. The burner is connected to the gas valve through a rubber tube. Make sure that the gas regulator of Tirrill or Meker burner is closed before opening the gas valve. In Bunsen burner, the flow of gas is regulated directly through the gas valve. Take note of the following precautions and safety reminders when operating laboratory burners: 1. Remove all combustible materials away from the working area. 2. Inspect the connecting hose of the burner for holes and any defects and make sure that it fits securely on the gas valve and on the burner.. It is advisable to use a sparker/lighter with extended nozzle to ignite a burner. 3. Close the gas regulator before opening the gas valve. 4. Adjust the flame by rotating the collar of the burner to open air holes and produce the desired flame for the experiment (luminous or non-luminous). A blue flame is ideal because it has the highest temperature and do not produce soot. 5. Never leave an open flame unattended and turn the burner off while not in use. When heating substances in a test tube directly into the flame, grasp the test tube with a test tube holder and incline it at approximately 45o and away from any person. Move the test tube by passing it back and forth over the flame. Shake the test tube occasionally and avoid inhaling the generated fumes or vapor except as directed. When such fume or vapor needs to be smelled, do not smell them directly but rather waft the fume or vapor to your nose with fanning motion of your hand. Flammable substances should never be heated with open flame! Instead they are heated using a water or steam bath. 4. Transferring of Reagents Solid and liquid chemicals are usually kept in reagent bottles. When the stopper or lid of the reagent bottle is removed, put it upside down on the laboratory table or fume hood to avoid contamination. Dark reagent bottles are used for light-sensitive chemicals to prevent them from decomposition. Liquid chemicals can be transferred by carefully  pouring through the topside of the container or using a pipette properly as directed earlier. Meanwhile, solid chemicals should be taken from a reagent bottle using a clean and dry spatula as a dirty spatula can contaminate the portion taken as well as the content of the bottle. One way of transferring solid reagents is to use a folded piece of paper to pour it into the container to be used in the experiment. Use a different spatula or pipette for each reagent to avoid cross-contamination. It is prudent to take only the amount of reagent that is needed in the experiment and to never return any unused chemical back into the reagent bottle. 5. Proper Filtration of Mixture Filtration is a process that is used to separate an insoluble solid from a liquid. The insoluble solid is commonly termed as residue or sediment and if it is a result of a precipitation reaction, it is called a precipitate. The liquid portion is called filtrate. Filtration is done to isolate a valuable residue that is to remove impurities and to recover filtrate as a valuable component The procedure requires a barrier, usually a filter paper, to separate the components. 6. Glass Tubing Manipulations A glass tubing can be cut into smaller size using a triangular file. The glass tube is laid flat on the laboratory table and a circular scratch at the point to be cut is made using the file. A deeper scratch is preferable to lessen the pressure needed to break the glass. Using your thumbs opposite each other and about few centimeters from the scratch, gentle push is applied to cut the tube. The sharp edges of the glass tube is polished by rotating it at the non-luminous portion of a laboratory burner’s flame ; the process is called fire polishing. Meanwhile, to bend a glass tubing a wing top is attached to the barrel of a burner to spread a non-luminous flame evenly. The portion of the glass tube that will be bent is heated while rotating for even heat distribution. When the tubing is already hot enough, as manifested by yellow-orange color of the heated glass, it is removed from the flame and carefully bent into a smooth curve or desired angle. Safety Data Sheets, formerly known as Material Safety Data Sheets (MSDS) contains valuable information on chemicals as well as procedures on how to handle chemicals safely. —--------------------------------------------------------------------------------- MODULE 3 Calorimetry is a technique used for determining the amount of heat transferred during a physical or chemical process. In calorimeter, we have two types: Constant volume calorimeter (bomb calorimeter) for combustion reactions constant pressure calorimeter for non-combustion reactions such as heat of neutralization, Most types of calorimeters are made up of metals like aluminum and copper and for some economic considerations, a Styrofoam coffee cup can also be used as an alternative to the commercially available calorimeters. —--------------------------------------------------------------------------------- MODULE 4 Combustion, more commonly known as burning, is a rapid chemical reaction wherein a substance (called a fuel) reacts with atmospheric oxygen producing heat and usually light. —--------------------------------------------------------------------------------- ` MODULE 5 A voltaic or galvanic cell is a device that harnesses electrical energy from spontaneous redox reactions. It consists of two electrodes namely the anode (+) and cathode (-) where oxidation and reduction reactions occur respectively. The two solutions are connected by a salt bridge which is usually made up of a curved glass that is filled with electrolyte solution and plugged with a semi-porous cap like a cotton plug. —--------------------------------------------------------------------------------- Enchem 1L - Lab 1 - Final - It consists of chemistry laboratory apparatus.