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Laboratory Assignment Laboratory Techniques Date Lab Sec. Name Desk No. Identify the Technique Icon, at left, for each of the following techniques. Technique Icon Description of technique 1. To dispense chemicals, read the label at least twice before removing any chemical from the reagent bottle. 2. 3. 4. 5. 6. 7. 8. 9. Water or glycerol should be applied to the glass tubing and the hole in the rubber stopper before inserting the glass tubing. A centrifuge should be balanced with an even number of centrifuge/test tubes, placed across the rotor from one another, with equal volumes of liquid. The volume of a liquid or solution in calibrated volumetric glassware should be read using all- certain digits (from the labeled calibration marks on the glassware) plus one uncertain digit (the last digit that is the best estimate between the calibration marks)—that is, to the correct number of significant figures. The bowl of the funnel for gravity filtration should be always less than two-thirds full. To dispense a liquid from a pipet, first draw the liquid into the pipet 2–3 cm above the calibration mark with a pipet bulb and then use the index finger to control its flow. The suction created for the vacuum filtration of a precipitate is applied with an aspirator in which the water faucet is fully open. To prepare a solution, always add the solid reagent or more concentrated solution to a volumetric flask that is already approximately one-third full with solvent. While dispensing titrant from a buret, the stopcock should be operated with the left hand (if right- handed) and the Erlenmeyer flask should be swirled with the right hand. To heat a solid to high temperatures in the absence of air, place the solid in a crucible and fully cover the crucible with the crucible lid. Information on the properties and disposal of chemicals can be found in the stockroom or online from the MSDS collection. A buret should be rinsed with several 3- to 5-mL portions of titrant before being filled. Glassware is clean when no water droplets cling to the inner wall of the vessel. For heating a liquid in a test tube, the test tube should be less than one-third full, moved continu- ously in and out of the “cool” flame at a 45° angle, mostly near the top of the liquid. The volume of a liquid should be read at the bottom of the meniscus. Small quantities of liquids in test tubes are best be heated (safely) in a hot water bath with the heat source being either a hot plate or a direct flame. All chemicals must be properly disposed—either according to the Experimental Procedure or the laboratory instructor. Never place reagents directly onto the weighing pan of a balance—always use weighing paper, a beaker, or some other container. A hot plate (not an open flame) is the heat source for heating or evaporating flammable liquids. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Laboratory Techniques 41 20. 21. Dry Lab 1 22. 23. The tared mass of a sample is its mass without regard to its container. Transfer liquids and solutions from a reagent bottle or beaker with the aid of a stirring rod. A small” test tube has a volume of -3 mL. A litmus paper test for the acidity or basicity of a solution requires the use of a stirring rod to remove a portion of the solution to then be touched to the litmus paper. After drying a hygroscopic solid in a drying oven, the solid should be cooled in a desiccator. The color change of the indicator at the endpoint of a titration should persist for 30 seconds. The Laboratory and SI 24. 25. Courtesy of Thermo Fisher Scientific A set of standard Sl mass units. OBJECTIVES • To check into the laboratory • To become familiar with the laboratory and the laboratory manual To learn the rules of laboratory safety and the necessity of practicing these rules in the laboratory To learn how to properly organize and record laboratory data To develop skills in the use of Le Système International d'Unités (SI Units) INTRODUCTION Answer True or False for the following statements that refer to Laboratory Techniques. Ask your instructor to identify the questions you are to complete. 1. All clean glassware should be air-dried naturally. 2. While cleaning glassware, discard all washes and rinses from the delivery point of the glass vessel. 3. To avoid waste in the use of chemicals, share the unused portion with other chemists before discarding. 4. Never touch, taste, or smell a chemical unless specifically told to do so. 5. A chemical with a blue” hazard label (a number 3 rating) means that the chemical is highly reactive. 6. If uncertain as to how to dispose of a chemical, dumping it into the sink followed by copious amount of water is a safe disposal procedure. 7. Use a spatula to transfer solid chemicals from a reagent bottle. 8. Most all chemicals used in experiments can be discarded into the sink. 9. The number of significant figures used to record the mass of a chemical should correspond to the sensitiv- ity of the balance used for the measurement. 10. A 3-inch test tube has a volume of 3 mL; an 8-inch test tube must have a volume of 8 mL. 11. To transfer a solution, a stirring rod touches the delivery point of the reagent vessel and the wall of the receiving vessel 12. The minimum number of centrifuge tubes placed in a centrifuge during its operation is two. 13. A test tube should be less than one-third full when heating with a "cool” flame. 14. Right-handed students should operate the stopcock of a buret with their left hand and swirl the Erlenmeyer (receiving) flask with the right hand. 15. The thumb is the digit of choice on controlling the flow of liquid from a pipet. 16. Blow out the solution remaining in the pipet tip after the solution has drained from the pipet. 17. A buret must always be filled to the top (the zero mark) before every titration procedure. 18. The volume of solution in a buret should be read and recorded 10–15 seconds after completing the titration. 19. It is possible to add a half-drop of solution from a buret. _20. To test the acidity of a solution with pH paper, place the pH paper directly in the solution. 21. The odor of a chemical should not be tested unless specifically instructed to do so. The vapors of the chem- ical should be fanned toward the nose. 22. One must first calculate the number of moles of solute that are required before preparing a solution of known concentration. All chemical principles, tools, and techniques are developed in the laboratory. The experience of observing a chemical phenomenon and then explaining its behavior is one that simply cannot be gained by reading a textbook, listening to a lecturer, search- ing the Internet, or viewing a video. It is in the laboratory where chemistry comes alive, where chemical principles are learned and applied to the vast natural “chemistry laboratory” that we call our everyday environment. The objectives of a laboratory experience are to design and build apparatus, develop techniques, observe, record and interpret data, and deduce rational theories so that the real world of science is better explained and understood. In the laboratory, you will use common equipment and safe chemicals to perform experiments. You record your experimental observations and interpret the data on the basis of sound chemical principles. A good scientist is a thinking scientist trying to account for the observed data and rationalize any contradictory data. Cultivate self- reliance and confidence in your data, even if the data do not look right.” This is how many breakthroughs in science occur. Stuart Feinstein, author "Ignorance: How It Drives Science" In the first few laboratory sessions you will be introduced to some basic rules, equipment, and techniques and some situations where you use them. These include laboratory safety rules, Le Système International d'Unités (SI Units), the Bunsen burner, and the analytical balance. Additional laboratory techniques are illustrated under Laboratory Techniques pages 17–42; others are introduced as the need arises. "There is no surer way to screw up, an experiment than to be certain of its outcome." Procedure Overview: Laboratory procedures are introduced. A familiarity with laboratory apparatus, the policies regarding laboratory safety, the procedures for presenting laboratory data, and an encounter with the SI units are emphasized. DRY LAB PROCEDURE Summarize the Disclaimer in your own words. At the beginning of the first laboratory period, you are assigned a lab station containing A. Laboratory Check-in laboratory equipment. Place the laboratory equipment on the laboratory bench and, with 42 Laboratory Techniques Dry Lab 1 43 Beginning our solution to the problem with the measured quantity (i.e., 4.3 ng), we need to convert ng to g and g to ug using the appropriate conversion factors to obtain proper unit cancellation: Dry Lab 1 Report Sheet g ug Х = 4.3 X 10-3 ng ug 10g The Laboratory and SI 4.3 Kg X Date Lab Sec. Name Desk No. = A. Laboratory Check-In Instructor's approval Appendix A ng cancel g cancel ng ug ug The SI is compared with the English system in Table D1.2. SI units of measure- ment that chemists commonly use in the laboratory are listed in brackets. Appendix A has a more comprehensive table of conversion factors. Conversions between the SI and the English system are quite valuable, especially to Americans because international science and trade communications are in SI or metric units. Example D1.2 Using Tables D1.1 and D1.2, express the volume of 1.00 quart of water in terms of cubic centimeters. Solution. As 1 cm = 10-2 m, then 1 cm² = (102m) = (10-23 m?. From Table D1.2, we need unit conversion factors for quarts - liters, liters → m?, and finally mcm². Starting with 1.00 qt (our measured value in the problem), we have: 1 10-3mm 1.00 q x Х = 946 cm 1 Ł (10-33 cm 1.057 at B. Laboratory Safety and Guidelines Instructor's approval for completion of inside front cover Read Laboratory Safety and Guidelines on page 1-4 and answer the following as true or false. 1. Prescription glasses, which are required by law to be "safety glasses,” can be worn in place of safety goggles in the laboratory. 2. Sleeveless blouses and tank tops are not appropriate attire for the laboratory. 3. Only shoes that shed liquids are permitted in the laboratory. 4. "I just finished my tennis class. I can wear my tennis shorts to lab just this one time, right?" 5. Your laboratory has an eyewash fountain. 6. “Oops! I broke a beaker containing deionized water in the sink.” An accident as simple as that does not need to be reported to the laboratory instructor. 7. A beaker containing an acidic solution has broken on the bench top and spilled onto your clothes from the waist down and it burns. Ouch! You should immediately proceed to the safety shower and flood the affected area. 8. You received a paper cut on your finger and it is bleeding. Immediately go to the medicine cabinet to apply a disinfectant. 9. It is good laboratory protocol to inform other students when they are not practicing good laboratory safety procedures. If they continue to not follow the safety procedures, you should "rat" on them ... tell the laboratory instructor qt cancel L cancel mcancel qt L m' cm = cm Note again that the unit conversion factors in Example D1.2 do not change the magnitude of the measurement, only its form of expression. Since 1 cm = 1 mL, 1.00 quart is equivalent to 946 mL. The Report Sheet, Part E, further acquaints you with conversions within the SI and between SI and the English system. Ask your laboratory instructor which of the questions from Part E you are to complete on the Report Sheet. 10. Cell phones, iPods, and other electronic equipment should be turned off during the laboratory period. 11. Your friend is a senior chemistry major and thoroughly understands the difficult experiment that you are per- forming. Therefore, it is advisable (even recommended) that you invite him or her into the laboratory for direct assistance. 12. You missed lunch but brought a sandwich to the laboratory. Since you cannot eat in the lab, it is okay to leave the sandwich in the hallway and then go in and out to take bites while the laboratory experiment is ongoing. Write a short response for the following questions. 1. What does the phrase "neck to knee to wrist” mean with regard to laboratory safety? Table D1.2 Comparison of Le Système International d'Unités and English System of Measurements Physical Quantity SI Unit Conversion Factor Length meter (m) 1 km = 0.6214 mi 1 m = 39.37 in. 1 in. = 0.0254 m = 2.54 cm Volume cubic meter (m) 1 L = 10-m = 1 dm = 10mL [liter (L)) 1 mL = 1 cm IL = 1.057 qt 1 oz (fluid) = 29.57 mL Mass kilogram (kg) 1 lb = 453.6 g (gram (g)] 1 kg = 2.205 lb Pressure pascal (Pa) 1 Pa = 1 N/m (atmosphere (atm) 1 atm = 101.325 kPa = 760 torr 1 atm = 14.696 lb/in. (psi) Temperature kelvin (K) K= 273 + °C [degrees Celsius (°C)] °C= F-32 1.8 joule (1) 1 cal = 4.184 1 Btu = 1054 J ©Duane Osborn/Somos Images/Corbis 2. The first action after an accident occurs is: Energy 3. You want to try a variation of the Experimental Procedure because of your chemical curiosity. What is the proper pro- cedure for performing the experiment? Graduated cylinders of different volumes "The SI units enclosed in brackets are commonly used in chemical measurements and calculations. For additional conversion factors, go online to www.onlineconversion.com. 46 The Laboratory and SI Dry Lab 1 47 Experiment 1 Prelaboratory Assignment Basic Laboratory Operations mi 10 ml Volume of H20 plus metal Date Lab Sec. Name Desk No. 1. A proper fuel-air mixture is most critical in the production of an efficient, nonluminous flame. For the ignition of an efficient Bunsen flame in the laboratory, identify the most common) fuel and the required air component. Volume of H20 - Korcuso a la foto lo 2. a. What is the dominant color of a nonluminous flame from a Bunsen burner? Explain. o A. Beran/Trey Hernandez lo A. Beran/Trey Hernandez b. Is the temperature of a luminous flame greater or less than that of a nonluminous flame? Explain. Figure 1.5 Apparatus for measuring the density of a water-insoluble solid 3. Diagram the cross section of a graduated cylinder, illustrating how to read the meniscus. d. Remove the solid, dry it, and measure its volume a second time. 16a - பாடியுமா Disposal: Check with your instructor for the procedure of properly returning the solid sample. 6 160 16b E 4. Experimental Procedure, Part B. What is the sensitivity of the least sensitive balance most likely to be in your laboratory? Refer to Data Analysis, B for calculating average values. 2. Liquid, water a. Clean your smallest laboratory beaker. Using your assigned balance, measure and record its mass. Pipet 5 mL of water into the beaker. b. Measure and record the mass of the beaker and water. Calculate the density of water from the available data. Repeat the density determination for Trial 2.0 c. Collect and record the density value of water at room temperature from five additional laboratory measurements from classmates Calculate the average density of water at room temperature. 3. Liquid, unknown a. Dry the beaker and pipet. Ask the instructor for a liquid unknown and record its number. (Caution: The unknown liquid may be flammable. Do not inhale the fumes of the liquid; extinguish all flames.) b. Rinse the pipet with two 1-mL quantities of the unknown liquid and discard. Repeat the measurements of Part C.2, substituting the unknown liquid for the water. Repeat this experiment for Trial 2. Calculate the average density of the liquid. Flammable: capable of igniting in air (generally initiated with a flame or spark) 5. A woodfire in a fireplace typically has a yellow flame whereas a (natural) gas fire (for a kitchen stove) is typically blue. Explain why the appearance of the wood flame is yellow whereas the gas flame most often appears blue. Disposal: Check with your instructor. Dispose of the unknown liquid and the rinses in the Waste Liquids container. DJClaassen/iStockphoto The Next Step How might the density of an object less dense than water be determined—for example, packing peanuts, a slice of bread, a feather? How might the density of a water-soluble solid be determined? 54 Basic Laboratory Operations Experiment 1 55 6. Refer to Technique 16B. a. Remove the drop suspended from a pipet tip by ... Experiment 1 Report Sheet Richard Megna/Fundamental Photographs Basic Laboratory Operations b. The finger used to control the delivery of liquid from a pipet is the ... In OA/ beat OSI Date Lab Sec. Name Desk No. 116b c. What should be done with the last bit of liquid remaining in the pipet after delivery? A. Bunsen Burner 1. Instructor's Approval of a well-adjusted Bunsen flame: 2. a. At right, draw a sketch of the heat zones for a nonluminous flame as directed with the wire gauze positioned parallel to the burner barrel. Label the "cool" and "hot" zones. b. What happens to the "cool" and "hot" zones of a nonluminous flame, when the air-control valve is closed (nearly closed)? Explain. d. Most pipets are calibrated as TD 20°C. Define TD; what is its meaning regarding the volume of liquid a pipet delivers? 7. Experimental Procedure, Part C.1. The density of diamond is 3.51 g/cm², and the density of platinum is 21.43 g/cm°. If equal masses of diamond and platinum are transferred to equal volumes of water in separate graduated cylinders, which graduated cylinder would have the greatest volume change? Explain or show with a sample calculation. B. Laboratory Balances 1. Determine the mass of the following objects on your assigned balance. Express your results with the correct sensitivity. Balance no. Sensitivity Description of Object Object (size or volume) Test tube Mass (g) Beaker Spatula Graduated cylinder 8. Experimental Procedure, Part C.3. The mass of a beaker is 5.333 g. After 5.00 mL of a concentrated hydrochloric acid solution is pipetted into the beaker, the combined mass of the beaker and the hydrochloric acid sample is 11.229 g. From the data, what is the measured density of the hydrochloric acid solution? Other (see instructor) 2. Precision of Measurement. Balance no. Mass of graduated cylinder (if not tared) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 a. Mass of cylinder +H,O (1) (8) b. Mass of 7 mL HO(1) (8) c. Average mass of 7 mL HO(1) (3) Data Analysis, B Comment on the precision of the mass measurements for the water samples. 56 Basic Laboratory Operations Experiment 1 57 Laboratory Assignment Laboratory Techniques Date Lab Sec. Name Desk No. Identify the Technique Icon, at left, for each of the following techniques. Technique Icon Description of technique 1. To dispense chemicals, read the label at least twice before removing any chemical from the reagent bottle. 2. 3. 4. 5. 6. 7. 8. 9. Water or glycerol should be applied to the glass tubing and the hole in the rubber stopper before inserting the glass tubing. A centrifuge should be balanced with an even number of centrifuge/test tubes, placed across the rotor from one another, with equal volumes of liquid. The volume of a liquid or solution in calibrated volumetric glassware should be read using all- certain digits (from the labeled calibration marks on the glassware) plus one uncertain digit (the last digit that is the best estimate between the calibration marks)—that is, to the correct number of significant figures. The bowl of the funnel for gravity filtration should be always less than two-thirds full. To dispense a liquid from a pipet, first draw the liquid into the pipet 2–3 cm above the calibration mark with a pipet bulb and then use the index finger to control its flow. The suction created for the vacuum filtration of a precipitate is applied with an aspirator in which the water faucet is fully open. To prepare a solution, always add the solid reagent or more concentrated solution to a volumetric flask that is already approximately one-third full with solvent. While dispensing titrant from a buret, the stopcock should be operated with the left hand (if right- handed) and the Erlenmeyer flask should be swirled with the right hand. To heat a solid to high temperatures in the absence of air, place the solid in a crucible and fully cover the crucible with the crucible lid. Information on the properties and disposal of chemicals can be found in the stockroom or online from the MSDS collection. A buret should be rinsed with several 3- to 5-mL portions of titrant before being filled. Glassware is clean when no water droplets cling to the inner wall of the vessel. For heating a liquid in a test tube, the test tube should be less than one-third full, moved continu- ously in and out of the “cool” flame at a 45° angle, mostly near the top of the liquid. The volume of a liquid should be read at the bottom of the meniscus. Small quantities of liquids in test tubes are best be heated (safely) in a hot water bath with the heat source being either a hot plate or a direct flame. All chemicals must be properly disposed—either according to the Experimental Procedure or the laboratory instructor. Never place reagents directly onto the weighing pan of a balance—always use weighing paper, a beaker, or some other container. A hot plate (not an open flame) is the heat source for heating or evaporating flammable liquids. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Laboratory Techniques 41 20. 21. Dry Lab 1 22. 23. The tared mass of a sample is its mass without regard to its container. Transfer liquids and solutions from a reagent bottle or beaker with the aid of a stirring rod. A small” test tube has a volume of -3 mL. A litmus paper test for the acidity or basicity of a solution requires the use of a stirring rod to remove a portion of the solution to then be touched to the litmus paper. After drying a hygroscopic solid in a drying oven, the solid should be cooled in a desiccator. The color change of the indicator at the endpoint of a titration should persist for 30 seconds. The Laboratory and SI 24. 25. Courtesy of Thermo Fisher Scientific A set of standard Sl mass units. OBJECTIVES • To check into the laboratory • To become familiar with the laboratory and the laboratory manual To learn the rules of laboratory safety and the necessity of practicing these rules in the laboratory To learn how to properly organize and record laboratory data To develop skills in the use of Le Système International d'Unités (SI Units) INTRODUCTION Answer True or False for the following statements that refer to Laboratory Techniques. Ask your instructor to identify the questions you are to complete. 1. All clean glassware should be air-dried naturally. 2. While cleaning glassware, discard all washes and rinses from the delivery point of the glass vessel. 3. To avoid waste in the use of chemicals, share the unused portion with other chemists before discarding. 4. Never touch, taste, or smell a chemical unless specifically told to do so. 5. A chemical with a blue” hazard label (a number 3 rating) means that the chemical is highly reactive. 6. If uncertain as to how to dispose of a chemical, dumping it into the sink followed by copious amount of water is a safe disposal procedure. 7. Use a spatula to transfer solid chemicals from a reagent bottle. 8. Most all chemicals used in experiments can be discarded into the sink. 9. The number of significant figures used to record the mass of a chemical should correspond to the sensitiv- ity of the balance used for the measurement. 10. A 3-inch test tube has a volume of 3 mL; an 8-inch test tube must have a volume of 8 mL. 11. To transfer a solution, a stirring rod touches the delivery point of the reagent vessel and the wall of the receiving vessel 12. The minimum number of centrifuge tubes placed in a centrifuge during its operation is two. 13. A test tube should be less than one-third full when heating with a "cool” flame. 14. Right-handed students should operate the stopcock of a buret with their left hand and swirl the Erlenmeyer (receiving) flask with the right hand. 15. The thumb is the digit of choice on controlling the flow of liquid from a pipet. 16. Blow out the solution remaining in the pipet tip after the solution has drained from the pipet. 17. A buret must always be filled to the top (the zero mark) before every titration procedure. 18. The volume of solution in a buret should be read and recorded 10–15 seconds after completing the titration. 19. It is possible to add a half-drop of solution from a buret. _20. To test the acidity of a solution with pH paper, place the pH paper directly in the solution. 21. The odor of a chemical should not be tested unless specifically instructed to do so. The vapors of the chem- ical should be fanned toward the nose. 22. One must first calculate the number of moles of solute that are required before preparing a solution of known concentration. All chemical principles, tools, and techniques are developed in the laboratory. The experience of observing a chemical phenomenon and then explaining its behavior is one that simply cannot be gained by reading a textbook, listening to a lecturer, search- ing the Internet, or viewing a video. It is in the laboratory where chemistry comes alive, where chemical principles are learned and applied to the vast natural “chemistry laboratory” that we call our everyday environment. The objectives of a laboratory experience are to design and build apparatus, develop techniques, observe, record and interpret data, and deduce rational theories so that the real world of science is better explained and understood. In the laboratory, you will use common equipment and safe chemicals to perform experiments. You record your experimental observations and interpret the data on the basis of sound chemical principles. A good scientist is a thinking scientist trying to account for the observed data and rationalize any contradictory data. Cultivate self- reliance and confidence in your data, even if the data do not look right.” This is how many breakthroughs in science occur. Stuart Feinstein, author "Ignorance: How It Drives Science" In the first few laboratory sessions you will be introduced to some basic rules, equipment, and techniques and some situations where you use them. These include laboratory safety rules, Le Système International d'Unités (SI Units), the Bunsen burner, and the analytical balance. Additional laboratory techniques are illustrated under Laboratory Techniques pages 17–42; others are introduced as the need arises. "There is no surer way to screw up, an experiment than to be certain of its outcome." Procedure Overview: Laboratory procedures are introduced. A familiarity with laboratory apparatus, the policies regarding laboratory safety, the procedures for presenting laboratory data, and an encounter with the SI units are emphasized. DRY LAB PROCEDURE Summarize the Disclaimer in your own words. At the beginning of the first laboratory period, you are assigned a lab station containing A. Laboratory Check-in laboratory equipment. Place the laboratory equipment on the laboratory bench and, with 42 Laboratory Techniques Dry Lab 1 43 Beginning our solution to the problem with the measured quantity (i.e., 4.3 ng), we need to convert ng to g and g to ug using the appropriate conversion factors to obtain proper unit cancellation: Dry Lab 1 Report Sheet g ug Х = 4.3 X 10-3 ng ug 10g The Laboratory and SI 4.3 Kg X Date Lab Sec. Name Desk No. = A. Laboratory Check-In Instructor's approval Appendix A ng cancel g cancel ng ug ug The SI is compared with the English system in Table D1.2. SI units of measure- ment that chemists commonly use in the laboratory are listed in brackets. Appendix A has a more comprehensive table of conversion factors. Conversions between the SI and the English system are quite valuable, especially to Americans because international science and trade communications are in SI or metric units. Example D1.2 Using Tables D1.1 and D1.2, express the volume of 1.00 quart of water in terms of cubic centimeters. Solution. As 1 cm = 10-2 m, then 1 cm² = (102m) = (10-23 m?. From Table D1.2, we need unit conversion factors for quarts - liters, liters → m?, and finally mcm². Starting with 1.00 qt (our measured value in the problem), we have: 1 10-3mm 1.00 q x Х = 946 cm 1 Ł (10-33 cm 1.057 at B. Laboratory Safety and Guidelines Instructor's approval for completion of inside front cover Read Laboratory Safety and Guidelines on page 1-4 and answer the following as true or false. 1. Prescription glasses, which are required by law to be "safety glasses,” can be worn in place of safety goggles in the laboratory. 2. Sleeveless blouses and tank tops are not appropriate attire for the laboratory. 3. Only shoes that shed liquids are permitted in the laboratory. 4. "I just finished my tennis class. I can wear my tennis shorts to lab just this one time, right?" 5. Your laboratory has an eyewash fountain. 6. “Oops! I broke a beaker containing deionized water in the sink.” An accident as simple as that does not need to be reported to the laboratory instructor. 7. A beaker containing an acidic solution has broken on the bench top and spilled onto your clothes from the waist down and it burns. Ouch! You should immediately proceed to the safety shower and flood the affected area. 8. You received a paper cut on your finger and it is bleeding. Immediately go to the medicine cabinet to apply a disinfectant. 9. It is good laboratory protocol to inform other students when they are not practicing good laboratory safety procedures. If they continue to not follow the safety procedures, you should "rat" on them ... tell the laboratory instructor qt cancel L cancel mcancel qt L m' cm = cm Note again that the unit conversion factors in Example D1.2 do not change the magnitude of the measurement, only its form of expression. Since 1 cm = 1 mL, 1.00 quart is equivalent to 946 mL. The Report Sheet, Part E, further acquaints you with conversions within the SI and between SI and the English system. Ask your laboratory instructor which of the questions from Part E you are to complete on the Report Sheet. 10. Cell phones, iPods, and other electronic equipment should be turned off during the laboratory period. 11. Your friend is a senior chemistry major and thoroughly understands the difficult experiment that you are per- forming. Therefore, it is advisable (even recommended) that you invite him or her into the laboratory for direct assistance. 12. You missed lunch but brought a sandwich to the laboratory. Since you cannot eat in the lab, it is okay to leave the sandwich in the hallway and then go in and out to take bites while the laboratory experiment is ongoing. Write a short response for the following questions. 1. What does the phrase "neck to knee to wrist” mean with regard to laboratory safety? Table D1.2 Comparison of Le Système International d'Unités and English System of Measurements Physical Quantity SI Unit Conversion Factor Length meter (m) 1 km = 0.6214 mi 1 m = 39.37 in. 1 in. = 0.0254 m = 2.54 cm Volume cubic meter (m) 1 L = 10-m = 1 dm = 10mL [liter (L)) 1 mL = 1 cm IL = 1.057 qt 1 oz (fluid) = 29.57 mL Mass kilogram (kg) 1 lb = 453.6 g (gram (g)] 1 kg = 2.205 lb Pressure pascal (Pa) 1 Pa = 1 N/m (atmosphere (atm) 1 atm = 101.325 kPa = 760 torr 1 atm = 14.696 lb/in. (psi) Temperature kelvin (K) K= 273 + °C [degrees Celsius (°C)] °C= F-32 1.8 joule (1) 1 cal = 4.184 1 Btu = 1054 J ©Duane Osborn/Somos Images/Corbis 2. The first action after an accident occurs is: Energy 3. You want to try a variation of the Experimental Procedure because of your chemical curiosity. What is the proper pro- cedure for performing the experiment? Graduated cylinders of different volumes "The SI units enclosed in brackets are commonly used in chemical measurements and calculations. For additional conversion factors, go online to www.onlineconversion.com. 46 The Laboratory and SI Dry Lab 1 47 Experiment 1 Prelaboratory Assignment Basic Laboratory Operations mi 10 ml Volume of H20 plus metal Date Lab Sec. Name Desk No. 1. A proper fuel-air mixture is most critical in the production of an efficient, nonluminous flame. For the ignition of an efficient Bunsen flame in the laboratory, identify the most common) fuel and the required air component. Volume of H20 - Korcuso a la foto lo 2. a. What is the dominant color of a nonluminous flame from a Bunsen burner? Explain. o A. Beran/Trey Hernandez lo A. Beran/Trey Hernandez b. Is the temperature of a luminous flame greater or less than that of a nonluminous flame? Explain. Figure 1.5 Apparatus for measuring the density of a water-insoluble solid 3. Diagram the cross section of a graduated cylinder, illustrating how to read the meniscus. d. Remove the solid, dry it, and measure its volume a second time. 16a - பாடியுமா Disposal: Check with your instructor for the procedure of properly returning the solid sample. 6 160 16b E 4. Experimental Procedure, Part B. What is the sensitivity of the least sensitive balance most likely to be in your laboratory? Refer to Data Analysis, B for calculating average values. 2. Liquid, water a. Clean your smallest laboratory beaker. Using your assigned balance, measure and record its mass. Pipet 5 mL of water into the beaker. b. Measure and record the mass of the beaker and water. Calculate the density of water from the available data. Repeat the density determination for Trial 2.0 c. Collect and record the density value of water at room temperature from five additional laboratory measurements from classmates Calculate the average density of water at room temperature. 3. Liquid, unknown a. Dry the beaker and pipet. Ask the instructor for a liquid unknown and record its number. (Caution: The unknown liquid may be flammable. Do not inhale the fumes of the liquid; extinguish all flames.) b. Rinse the pipet with two 1-mL quantities of the unknown liquid and discard. Repeat the measurements of Part C.2, substituting the unknown liquid for the water. Repeat this experiment for Trial 2. Calculate the average density of the liquid. Flammable: capable of igniting in air (generally initiated with a flame or spark) 5. A woodfire in a fireplace typically has a yellow flame whereas a (natural) gas fire (for a kitchen stove) is typically blue. Explain why the appearance of the wood flame is yellow whereas the gas flame most often appears blue. Disposal: Check with your instructor. Dispose of the unknown liquid and the rinses in the Waste Liquids container. DJClaassen/iStockphoto The Next Step How might the density of an object less dense than water be determined—for example, packing peanuts, a slice of bread, a feather? How might the density of a water-soluble solid be determined? 54 Basic Laboratory Operations Experiment 1 55 6. Refer to Technique 16B. a. Remove the drop suspended from a pipet tip by ... Experiment 1 Report Sheet Richard Megna/Fundamental Photographs Basic Laboratory Operations b. The finger used to control the delivery of liquid from a pipet is the ... In OA/ beat OSI Date Lab Sec. Name Desk No. 116b c. What should be done with the last bit of liquid remaining in the pipet after delivery? A. Bunsen Burner 1. Instructor's Approval of a well-adjusted Bunsen flame: 2. a. At right, draw a sketch of the heat zones for a nonluminous flame as directed with the wire gauze positioned parallel to the burner barrel. Label the "cool" and "hot" zones. b. What happens to the "cool" and "hot" zones of a nonluminous flame, when the air-control valve is closed (nearly closed)? Explain. d. Most pipets are calibrated as TD 20°C. Define TD; what is its meaning regarding the volume of liquid a pipet delivers? 7. Experimental Procedure, Part C.1. The density of diamond is 3.51 g/cm², and the density of platinum is 21.43 g/cm°. If equal masses of diamond and platinum are transferred to equal volumes of water in separate graduated cylinders, which graduated cylinder would have the greatest volume change? Explain or show with a sample calculation. B. Laboratory Balances 1. Determine the mass of the following objects on your assigned balance. Express your results with the correct sensitivity. Balance no. Sensitivity Description of Object Object (size or volume) Test tube Mass (g) Beaker Spatula Graduated cylinder 8. Experimental Procedure, Part C.3. The mass of a beaker is 5.333 g. After 5.00 mL of a concentrated hydrochloric acid solution is pipetted into the beaker, the combined mass of the beaker and the hydrochloric acid sample is 11.229 g. From the data, what is the measured density of the hydrochloric acid solution? Other (see instructor) 2. Precision of Measurement. Balance no. Mass of graduated cylinder (if not tared) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 a. Mass of cylinder +H,O (1) (8) b. Mass of 7 mL HO(1) (8) c. Average mass of 7 mL HO(1) (3) Data Analysis, B Comment on the precision of the mass measurements for the water samples. 56 Basic Laboratory Operations Experiment 1 57
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Explanation & Answer

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11I
16A

11C
16B
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16C
15D
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16C
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13E
16A
13B
4
6
14b


6
11B
7A
17B
15B
16K

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True
True
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False
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False
True
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False
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True

The procedures outlined by this book are standard
guidelines however other steps may be needed to be safe.


Natural gas is the most common fuel and and the required air component is oxygen.

Blue, due to the complete combustion of gas in the air.

A luminous flame's temperature is less than that of a nonluminous flame as it involves insufficient supply of oxygen and therefore isn't as
energy ...


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