5. Do not bring food or drink into the laboratory: 6. Do not work in the laboratory alone.

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1 LAB 1. INTRODUCTION TO THE LABORATORY SAFETY AND TECHNIQUES PURPOSE: To learn safe practices for performing experiments and handling chemicals. To become familiar with the function and use of common laboratory equipment. To learn techniques of measuring mass and volume To separate a mixture of salt and sand into its components. To calculate the % composition of an unknown mixture. BACKGROUND: Government regulations require educational laboratories, as well as industry, to establish and maintain safe laboratory conditions. Laboratory instructors and students are responsible for maintaining a safe atmosphere and complying with the established guidelines and rules of the lab. The federal government established agency called the Occupational Safety and Health Administration (OSHA) is responsible for establishing standards to protect the safety and health of the national workforce. Violations of OSHA safety regulations lead to very serious and/or costly consequences. The chemistry laboratory with its equipment, glassware, and chemicals has the potential for accidents. By following the rules for handling chemicals safely and carrying out only the approved procedures, you will create a safe environment in the laboratory. SAFETY RULES: We have done our best to build safety into the design of the experiments and the work areas. You need to do your part in assuring that your laboratory experience is rewarding and safe. Know the following rules and abide by them whenever you enter the laboratory: Preparing for Laboratory work: 1. Pre-read. Before you come to lab read the discussion and directions for the experiment you will be doing. Make sure you know what the experiment is about and any safety concerns or hazards to expect. 2. Know the location and how to operate the eyewash fountains, safety showers, fire extinguisher, fire blanket, sand bucket, first aid kit, hoods, and exits. 3. Protect your eyes. Where chemical splash-proof safety goggles at all times. Contact lenses may be worn in the lab provided that safety goggles are worn over them. Contact lenses without goggles are dangerous because splashed chemicals make them difficult to remove. If chemicals accumulate under a lens, permanent eye damage can result. If a chemical should splash into your eyes, flood the eyes with water at the eyewash fountain. Continue to rinse with water for at least 10 minutes. 4. Dress appropriately: Wear shoes that cover your feet. Wear clothes that cover your torso and legs. Wear lab aprons if you wish. Long hair should be tied back so it does not fall into chemicals or a flame. 5. Do not bring food or drink into the laboratory: 6. Do not work in the laboratory alone. Handling Chemicals and Equipment Safely: 7. Handle glass equipment with care. Clean-up broken glass immediately and place in specially marked containers. Remember that hot glass doesn t look hot. 8. Do not taste chemicals. Smell vapors cautiously. Never pipette solution by mouth. When required to note the odor of a chemical, first take a deep breath of fresh air and hold it while you use your hand to fan some vapors toward your nose and note the odor. Do not inhale the fumes directly. If a compound gives off an irritating vapor, use it in the fume hood to avoid exposure. CH110 Lab 1. Introduction to the Laboratory (W14) 1

2 9. Follow safe procedures to avoid injury to yourself or others. Be aware of your neighbors activities and advise them of unsafe practices. Do not do unauthorized experiments. Do not put flammable chemicals near an open flame. Never heat a closed container as pressure inside can build and cause an explosion. To heat a substance in a test tube, use a test tube holder and hold the test tube at an angle moving continuously through the flame. Never point the open end of the test tube at anyone or look directly into it. 10. Dispose of chemicals safely. Clean up chemical spills immediately. Small spills of liquid chemicals can be cleaned up with a paper towel. Large chemical spills must be treated with absorbing material such as cat litter. Do not pour chemicals down the sink or put in trash can without authorization. Use waste containers that are provided to dispose of toxic or hazardous chemicals. If an irritating chemical contacts the skin, wash immediately with soap and copious amounts of water. Any clothing soaked with a chemical must be removed immediately because an absorbed chemical can continue to damage the skin. 11. Do not contaminate primary chemicals. Do not insert anything into stock bottles without authorization. Never return unused chemicals to stock bottles; only take the amount you will need by transferring it to a small, clean container. Keep rubber and glass stoppers off the bench top. 12. Notify your instructor of concerns. Report all injuries, spills, or accidents. Let your instructor know if you have health concerns or you are pregnant. 13. Maintain a neat and orderly lab. Place your books, bags, coats, etc. in the area under the sinks or on the hooks at the back of the lab. Keep aisles and work areas clear. Maintain a clean benchtop and drawer. Avoid excess visitors in the lab. 14. Clean up. Wash your hands etc before leaving the laboratory. Leave your work areas wiped clean for the next class. CHEMICAL HAZARD LABELING: The general hazard of a chemical are often presented in a spatial arrangement of numbers and colors developed by the National Fire Protection Association (NFPA). NFPA hazard ratings range from 1 (little hazard) to 4 (extreme hazard). The flammability rating (in red) which indicates the potential for burning is at twelve o clock. The reactivity rating (in yellow) at the three o clock position indicates the instability of the material by itself or with water with subsequent release of energy. The health rating (in blue) at the nine o clock position indicates the likelihood that a material will cause injury due to exposure by contact, inhalation, or ingestion.. At the six o clock position, information may be given on any special reactivity of the substance. For example, if there is unusual reactivity with water, the symbol W (do not mix with water) Flammability (red) Health (blue) Reactivity (yellow) Special Hazard 2 CH110 Lab 1. Introduction to the Laboratory (W14)

3 NFPA Health Hazard Rating: Color BLUE Rating Type of Possible Injury 4 Could cause death or major residual injury 3 On short exposure could cause serious temporary or residual injury 2 On exposure would cause irritation but only minor residual injury 1 On exposure would cause irritation but only minor residual injury 0 Under fire conditions would offer no hazard beyond that of ordinary combustible material. NFPA Flammability Hazard Rating: Color RED Rating Susceptibility of Materials to Burning 4 Will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature, or readily disperses in air and burns readily 3 Liquids and solids that can be ignited under almost all ambient temperature conditions. 2 Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. 1 Must be preheated before ignition can occur. 0 Will not burn NFPA Reactivity (Stability) Hazard Rating: Color YELLOW Rating Susceptibility to Release of Energy 4 Readily capable of detonation or of explosive decomposition or reaction at normal temperatures and pressures. 3 Capable of detonation or explosion or reaction but which require a strong initiating source or must be heated under confinement before initiation or react explosively with water. 2 Readily undergo violent chemical change at elevated temperatures and pressures or react violently with water or may form explosive mixtures with water. 1 Normally stable, but can become unstable at elevated temperatures and pressures. 0 Normally stable, even under fire exposure conditions, and are not reactive with water. NFPA Specific Hazard Rating: Rating W OX Special Hazard Demonstrates unusual reactivity with water Demonstrates oxidizing properties MATERIAL SAFETY DATA SHEETS: Material Safety Data Sheets (MSDS s) are safety reports that must be supplied with each chemical purchased. They list a variety of information about chemicals such as: Threshold limit values (TLV) which indicate the average concentration of a chemical that most people can be exposed to for a working lifetime with no ill effects. When exposed to substances in concentrations near the TLV, an individual may begin to experience mild dizziness, headache, and lassitude. Permissible exposure limit (PEL) which is a legal standard established by OSHA and is often identical to the TLV. Warnings or precautions, such as whether the chemical can be absorbed through intact skin, and they may suggest appropriate protective wear. LD 50, a common measure of toxicity. The LD 50 is the dose of the substance which is most likely to cause death within 14 days in one half (50%) of the animals tested. Different species of animals have different LD 50 s and they vary by method of exposure such as oral ingestion, skin contact, or inhalation of vapors. Lethal doses vary by body weight, so LD 50 s are reported in units of milligrams of toxic substance per kilogram of animal body weight (mg/kg). Common or alternate names. Many substances are known by more than one name. CH110 Lab 1. Introduction to the Laboratory (W14) 3

4 CAS number. To help prevent confusion over similar and alternate names, the Chemical Abstracts Service (CAS) of the American Chemical Society (ACS) has assigned a unique number to every substance. THE MERCK INDEX: Another useful source of hazard information is the Merck Index. This one-volume encyclopedia of chemicals is published by Merck & Co, Inc and contains more than 10,000 chemicals and lists alternate names, CAS numbers, formulas, structure, physical data, medical and nonmedical uses. The Merck Index has a strong medical character but it is very useful for all users of chemicals. LABORATORY TECHNIQUES: Measuring Volume: Graduated Cylinders are tools for accurately measuring the volume of liquids. They have more accurate markings than a beaker or Erlenmeyer flask, but have less accurate markings than a pipette, buret, or syringe. All types of volumetric glassware have a slender, cylindrical shape in the measuring region which causes the surface of most liquids to be curved downward. Take readings from the bottom of the curved surface (called the meniscus) with your eye at the same level. A: Read the bottom of a concave meniscus. B: Read the top of a convex meniscus. If the volumetric glassware that you are using has a number of graduations, estimate the volume as accurately as you can by noting the position of the meniscus between the graduations. See Figure Figure 2-5 The proper method of reading the meniscus. The reading is 85.5 ml. The scale divisions on a graduated cylinder are generally determined by its size. For example, the 50- ml graduated cylinder is divided into 1 ml increments. However, the scale of a 10-mL graduated cylinder is divided into 0.1 ml increments, and the scale of a 500-mL graduated cylinder is divided into 5 ml increments. The graduated cylinder scale is a ruled scale, and it is read like a ruler. Measuring Mass: When performing chemical reactions in the laboratory we often need to measure the mass of our ingredients. The techniques for measuring mass using an electronic balance will be explained and practiced in the experimental section of this lab. Our balances measure mass in grams. 4 CH110 Lab 1. Introduction to the Laboratory (W14)

5 Filtration: Filtration is the common process used to separate an insoluble solid from a liquid. Layers of rock and sand and algae are used to filter impurities from water to make it drinkable. Breweries use fine millipore filters to filter out harmful bacteria. In the laboratory the filtration process is carried out using a funnel and filter paper. The liquid that passes through the filter paper is called the filtrate, and the solid that remains on the filter paper is the precipitate or residue. Evaporation: Most substances that dissolve in a liquid (solutes) can be recovered from solution by evaporating the liquid portion (the solvent) over a direct flame, a hot plate, or a steam bath. The size of solid crystals often relates to the rate of evaporation of the solvent. Slowly formed crystals are usually larger than crystals formed rapidly. PROCEDURES: ACTIONS: I. LABORATORY LAYOUT: 1. Complete the lab diagram showing the position of the requested safety and laboratory equipment. II. SAFETY QUIZ: 2. Complete the safety quiz. III. HAZARD LABELING: 3. Complete the hazard labeling questions. IV. MEASUREMENTS: MASS 1. Obtain a weighing boat or shiny weighing paper 1 and place it on the pan of an electronic balance. Press the Tare or Zero button on the face of your balance to set the mass of the paper to zero With your lab scoop or metal spatula, put enough salt/sand mixture on the weighing paper to measure about 3 2 grams. Record the exact mass on your report sheet (Box IA) to 3 places behind the decimal according to the accuracy of your balance. 3. Carefully remove the weighing paper with the salt/sand mixture from the balance and transfer it to a 125 ml or 250 ml Erlenmeyer flask. 4 NOTES: 1 Chemical powders and liquids should never be placed directly on the metal balance pan since they may cause corrosion. Shiny paper or boats are used so that powdered materials will slide off easily. If porous paper, like filter paper or paper towels, were used instead of shiny materials, then powders might get caught in the fibers and be lost. If you are using weighing paper then fold it into quarters by folding in half, opening, and then folding in half again the other direction. Open up the paper and place it on the balance pan. 2 The tare button will set the recorded weight of your paper to grams. Now when you add solid to the paper the balance will show only the added mass of the solid. If you do not tare the balance after the weighing paper is applied, then you would have to subtract the mass of the paper from your total mass to get the mass of your substance alone. 3 The mass does not have to be exactly grams but could be anywhere between and ( ); (for example or etc.) 4 The shape of an Erlenmeyer flask makes swirling/mixing materials less likely to splash or spill than if done in a beaker. CH110 Lab 1. Introduction to the Laboratory (W14) 5

6 VOLUME: 4. Measure 7 mls of water using a graduated cylinder 5. The bottom of the meniscus 6 should be right at the 7 ml line of the graduated cylinder. 5. In Box IB of your report sheet draw a picture of the meniscus in your graduated cylinder. Include a couple of graduation markings on your cylinder drawing above and below. V. SEPARATION OF SALT AND SAND: 6. Add the 7 mls of deionized water from the graduated cylinder to the Erlenmeyer flask of salt/sand mixture. Swirl to completely dissolve the salt to make a salt water solution Mass two porcelain evaporating dishes. 11 One for sand and one for salt. Record these values.(box IIC & D) 8 8. Set up a ring stand with an iron ring and a funnel suspended over the massed porcelain evaporating dish for salt. 9. Flute 9 a piece of filter paper (or a coffee filter) and insert it into the funnel. 10. Perform a filtration by periodically swirling the Erlenmeyer flask solution of salt with sand to keep it mixed, and pouring the solution down a stirring rod 10 into the filter paper. 11. Rinse any residual materials from the Erlenmeyer flask into the filter using a squirt bottle of deionized water. 12. Remove the filter paper containing the sand residue and transfer the sand with a lab scoop or spatula to the massed porcelain dish for sand. 13. Place the porcelain evaporating dishes containing the filtrate salt solution and the residue sand on a hot plate and slowly 13 heat to evaporate the water from them. 14. Mass each of the evaporating dishes with the now dry salt (Box IIA) and sand (Box IIB) and subtract the mass of the respective dishes (IIC & IID) to determine the final masses of salt (IIE) and sand (IIF) collected Determine the percent 12 of salt (IIG) and percent of sand (IIH) in your original mixture. 16. Describe the salt crystals formed. 17. Assess the quality of your results and make some conclusions about your data For fine control of your water level you can use an eye dropper for the last bit of water. Always hold eye droppers upright with the glass tip pointing down. Natural vacuum will keep the liquid from spilling. Do not tip the dropper back or the vacuum will be broken and the filling will run into the bulb and get contaminated, or air may enter the dropper and cause the contents to spill. 6 Water forms a meniscus in any glass tube or cylinder because water is attracted to glass and will try to climb the sides of a glass container. We measure the amount of water in a glass tube from the bottom of the meniscus. 7 If the salt is not completely dissolved then it will remain solid and be filtered out of solution with the sand. Thus your results will show less salt and more sand than actually present. 8 Keep the dishes separate so you know which dish goes with which mass. 9 To flute filter paper: 1) fold in half 2) fold again into quarters 3) fold back and forth from the point as if making a fan 4) unfold the paper into a cone that will fit into a funnel. 1) 2) 3) 4) 10 The stirring rod helps to channel the flow of liquid to prevent dripping. 11 You ll subtract the mass of the evaporating dish from the mass of the dish/salt combination to determine the mass of salt. 12 Percent composition is the part divided by the whole X 100 or: part X 100 = % whole In this case the whole is the mass of the original salt and sand mixture. The part is the mass of the sand or the mass of the salt. 13 Heat slowly so the solution doesn t splatter. Stirring with a glass stirring rod may also help prevent spattering. 14 Do your percent compositions of salt and sand total 100? Why or why not? What might some of the errors be in your procedures or techniques? 6 CH110 Lab 1. Introduction to the Laboratory (W14)

7 LAB 1 INTRO TO THE LABORATORY REPORT: NAME PARTNER DATE I. LABORATORY LAYOUT: Draw a floor plan of your laboratory showing the location of the following features: Draw a dotted line to show your shortest escape route in the case of an emergency. Ex Exits FX Fire extinguisher FA First aid kit. W Your workstation FB Fire blanket H Hoods EW Eyewash SB Sand bucket BG Broken glass waste. SS Safety shower HALL II. Safety Quiz: 1. Approved eye protection is to be worn A. for certain experiments B. only for hazardous experiments C. all the time. 2. Eating in the laboratory is A. not permitted B. allowed at lunch time C. all right if you are careful 3. If you need to smell a chemical, you should A. inhale deeply over the tube B. take a breath of air and fan the vapors toward you C. put some of the chemical in your hand, and smell it. 4. Unauthorized experiments are A. all right as long as they don t seem hazardous. B. all right as long as no one finds out. C. not allowed. CH110 Lab 1. Introduction to the Laboratory (W14) 7

8 5. When heating liquids in a test tube, you should A. move the tube back and forth through the flame. B. Look directly into the open end of the test tube to see what is happening. C. Direct the open end of the tube away from other students. D. More than one of these but not all. 6. If a chemical is spilled on your skin, you should A. wait to see if it stings B. wash immediately with soap and lots of water. C. add another chemical to absorb it. 7. When taking liquids from a reagent bottle, A. use the clean droppers supplied. B. pour the reagent into a small container C. never pour back what you don t use. D. all of these. 8. In the laboratory, open-toed shoes or flip-flops and midriff tops are A. okay if the weather is hot B. all right if you wear a lab apron C. dangerous and should not be worn. 9. When is it all right to taste a chemical? A. Never B. When the chemical is not hazardous C. when you use a clean beaker 10. After you use a reagent bottle, A. keep it at your desk in case you need more B. return it to its proper location C. play a joke on your friends and hide it. 11. Before starting an experiment A. read the entire procedure B. ask your lab partner how to do the experiment C. skip to the laboratory report and try to figure out what to do. 12. Working alone in the laboratory without supervision is A. all right if the experiment is not too hazardous B. not allowed C. allowed if you are sure you can complete the experiment without help 13. You should wash your hands A. only if they are dirty B. before eating in the lab C. before you leave the lab 14. Personal items (books, coats, etc) should be A. kept on your lab bench B. left outside C. stored out of the way, 15. When you have taken too much of a chemical, you should A. give it to another student or ask about proper disposal. B. Return the excess to the reagent bottle C. store it in your lab drawer for future use. 16. In the lab, you should wear A. practical, protective clothing B. something fashionable C. your favorite clothes 17. If a chemical is spilled on the table, A. clean it up right away B. let the stockroom employees clean it up C. use appropriate absorbent if necessary D. more than one but not all of these. 18. A hazardous waste should be A. placed in a special waste container B. washed down the drain C. placed in the wastebasket 8 CH110 Lab 1. Introduction to the Laboratory (W14)

9 III. HAZARD LABELING: 1. Label the specific meaning of each part of the following label found on the following chemical labels. (What do these labels indicate to you that distinguish these specific chemicals?) A. B. 2 (red) 1 (red) 2 (blue) 4 (yellow) 4 (blue) 0 (yellow) 2. Which of the above labels is likely to be found on a bottle of nicotine a substance found in cigarette smoke? A or B? 3. Which of the above labels is likely to be found on a bottle of nitroglycerine, an explosive? A or B? IV. MEASUREMENTS: A. Mass Salt/Sand Mixture g B. Volume (Add labels & meniscus) II. SEPARATION OF SALT AND SAND A. Mass of Evaporation dish with Salt g C. Mass of Empty Evaporation dish for Salt g E. Mass of Salt alone g G. % Composition of Salt in the mixture: (show the calculations) B. Mass of Evaporating dish with Sand g D. Mass of Empty Evaporation dish for Sand g F. Mass of Sand alone g H. % Composition of Sand in the mixture: (show the calculations) ANALYSIS & CONCLUSIONS: Report the appearance of your separated salt and sand. Why doesn t your sum of salt and sand total 100 %.. CH110 Lab 1. Introduction to the Laboratory (W14) 9

10 LAB 1. INTRO TO THE LABORATORY: LAB EXERCISES: NAME DATE The curve of the surface of a liquid when placed in a cylindrical tube is called the A residue. B. filtrate. C. meniscus. D. tare To set the mass of an object to zero on an electronic balance is called to A residue. B. filtrate. C. meniscus. D. tare The material that passes through a filter is called the A residue. B. filtrate. C. meniscus. D. tare The material that remains in the filter paper after a filtration is called the A residue. B. filtrate. C. meniscus. D. tare 5. A student, Earl N. Meyer, is given a g sample of a mixture of salt and sand. Earl added water to the mixture, filtered out the sand, evaporated off the water from the salt and weighed his final products. He ended up with grams of salt and grams of sand. A. What was the % concentration of salt in Earl s mixture? Show your calculations B. What was the % concentration of sand in Earl s mixture? Show your calculations C. Assuming there were no mistakes in the reading of the balance, give some explanations for why the percent compositions of Earl s salt and sand don t total 100%. 6. If the water was allowed to evaporate from your salt water solution at a slow rate rather than quickly over a hot plate how might the crystals appear different? 10 CH110 Lab 1. Introduction to the Laboratory (W14)