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Solution Manual for Chemistry A Molecular Approach, 4th Edition

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    INSTRUCTOR MANUAL FOR LABORATORY MANUAL JOHN B. VINCENT AND ERICA LIVINGSTON CHEMISTRY A MOLECULAR APPROACH Fourth Edition NIVALDO J. TRO

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    ii Table of Contents Experiment 1 Laboratory B asics: Accuracy and P recision – Who’s the S hooting C hampion ? 1 Experiment 2 Components of a Mixture – What I s T hat S tuff in the B ottom of the C ereal B ox? 3 Experiment 3 Cathode Ray Tubes, Millikan Oil Drop, and Avogadro’s Number 5 Experiment 4 Conservation of Mass and Reaction Types – Copper Recovery Cycle 8 Experiment 5 Equivalent Weights and the Periodic Table 10 Experiment 6 Hydrates 12 Experiment 7 Gas Laws 14 Experiment 8 Styrofoam Cup Calorimetry: Atomic Weights 16 Experiment 9 Chemiluminescence: Glow S tick in a B eaker 19 Experiment 10 Atomic Spectra 22 Experiment 11 Reactivity of G roup 1 M etals – Yes, Mom, I T hrew S odium in W ater in C lass T oday 23 Experiment 12 Flame Tests – Flames and Smoke Bombs 26 Experiment 13 VSEPR and Molecular Models 29 Experiment 14 Simulating the Shroud of Turin: An Inquiry - based Experiment 31 Experiment 15 Taste Observe the rainbow: Paper C hromatography 34 Experiment 1 5B Chemical Oil Dispersant Experiment 36 Experiment 1 6 Sublimation 41 Experiment 1 7 Closest Packed Structures 43 Experiment 1 8 Colligative Properties – Freezing P oint D epression 47 Experiment 19A Diet Coke and Mentos – An Inquiry - B ased Experiment 49 Experiment 1 9B Kinetics: Testing for S emen – Acid P hosphatase 51 Experiment 19C Activation Energy Determination 54 Experiment 2 0 Equilibrium C onstants and LeChatelier’s P rinciple – CoCl 2 56 Experiment 2 1 Far from Equilibrium Systems: Creating Life in a Beaker 61 Experiment 2 2 Acid - base T itration 63 Experiment 2 3 Determining the B uffer C apacity of A ntacids 65 Experiment 2 4 Entropy – The C helate E ffect 67 Experiment 2 5 Redox Reactions – Detecting T races of B lood 69 Experiment 2 6 Radioactivity 72 Experiment 2 7A Group I Cations 75 Experiment 2 7B Group II Cations: “I love the smell of hydrogen sulfide – It smells like victory” 77 Experiment 2 7C Piltdown Man and Scientific Ethics 80 Experiment 2 7D Group IV Cations 83 Experiment 2 7E Anions 85 Experiment 2 8 Esters 87 Experiment 2 9 Which C ompounds A re G enotoxic or C arcinogens?: Cleaving P lasmid DNA and G el E lectrophoresis 89

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    iii Preface for Instructors When one of the authors was in high school deciding what major he would be in college, he was leaning toward chemistry. He favored chemistry over physics and mathematics because of what he had performed in chemistry lab with his own hands. Somehow there was something more to mixing the chemicals together and getting precipitates, gas bubbles, or color changes than watching a block slid e down an inclined plane. Getting into the lab and making something happen (i.e., blowing something up) or making something new is probably the inspiration for nearly all budding chemists. Chemistry is a “hands - on” science. How often do we say this to our students or to administrators to justify the expense of the lab? Chemists inherently understand this to be true. Seeing something happen is more educational and powerful than only discussing the theory behind it. At a fundamental level, chemistry occurs beyond the naked eye, beyond the grasp of most of our senses. One of the authors was fortunate in having an excellent laboratory experience in high school; he even got to throw tiny pieces of sodium metal into a beaker, rapidly cover the beaker with a watch glass , and observe what happens, for example. When he talks to old high school companions who went into other areas, they still remember this experiment. This is the kind of excitement we are aiming for in this laboratory manual project. We want students to see things for themselves and do things for themselves that will emphasize the concepts from the lecture portion of general chemistry. Most laboratory manuals seem to be a tired rehashing of the same material – all but interchangeable. The authors often seem to forget to ask whether the experiment would have been fun or exciting if they were a student. Thus, one finds dry “cookbook” laboratory manuals. The “cookbook” label is somewhat unfair as no matter what type of laboratory experiment is being performed (even an inquiry - based experiment), the students must be guided through the exercise. A novice observer cannot be expected to necessarily make the important observations without training into what is important to look for. With this in mind, we are attempting to devise a laboratory manual that is concept oriented, has varying levels of student guidance ranging from what is now called “inquiry - based” to classical “cookbook” and hands - on and exciting. Why should the professor in front of the class be the only one to perform the exciting chemistry of the lecture demonstrations? Why not have students throw sodium into water, make things glow in the dark, and mix chemicals together to get results they never could anticipate (as in an oscillating reaction)? We also believe that some issues not normally treated in the laboratory to an appreciable degree can be covered such as the scientific method and scientific ethics. All this can be handled, we believe, without straying too far from familiar territory to those individuals who must be in the trenches setting up experiments, teaching the lab, or directing graduate assistants. Thus, a variety of techniques to approach “traditional” experiments will be presented to students. Some are open ended. Some are inquiry driven. Some are driven by attempting to obtain an answer close to an accepted standard. Some are based on current event s , some on current “sensational” entertainment, and some on history. Through it all, our aim is to present concrete and graspable theories with experiment and example. We are including qualitative analysis in this manual. We believe the logic structure of this process, including using flow diagrams , is an important contribution to the course.

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    iv When we set out to write this manual , our intention was to have detailed waste - disposal procedures. As we looked into this issue, we found that local regulations and restrictions were so varied as to make this impractical. We have made notes of when items require particular care, regardless of location. Please work with your chemical hygiene officer to work out the proper conditions for your location. We hope you and your students can have fun and learn from what follows. In addition, please feel free to send us your comments or those of your colleagues and students. We appreciate any input so that we can continuously improve this manual. John B. Vincent and Erica Livingston

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    v General Laboratory and Safety Rules For the Instructor The general laboratory and safety rules are only intended to provide basics common to all general chemistry laboratories; they are not meant to be comprehensive or to cover the specialized needs of any particular laboratory situation and environment. Each instructor should provide details and edit the rules as necessary to their own situation. Instructors should acquaint themselves with more comprehensive laboratory safety publications such as Safety in Academic Chemistry Laboratories published by the American Chemical Society. 1 1. American Chemical Society Committee on Chemical Safety. Safety in Academic Chemistry Laboratories , 7 th ed. American Chemical Society: Washington, DC, 2003.

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    vi Name__________________________________________________ Student No:_______________________ Room & Day _____________________ Desk Number ________ Course & Section ____________________ Received Received In From In From Drawer Stockroom Price Drawer Stockroom Price _____ _____ 1 Beaker, 50ml $3.23 _____ _____ 1 Litmus paper, red $0.77 _____ _____ 1 Beaker, 100ml $4.35 _____ _____ 1 Litmus paper, blue $0.77 _____ _____ 1 Beaker, 250ml $4.20 _____ _____ 1 Pipet, serological (measuring) 10ml $10.60 _____ _____ 1 Beaker, 400ml $3.75 _____ _____ 6 Pipets, dropping, w/bulb $0.45 _____ _____ 1 Beaker, 600ml $6.18 _____ _____ 1 Spatula , scraper $9.10 _____ _____ 1 Bottle, Nalgene 250ml $1.73 _____ _____ 1 Sponge $1.84 _____ _____ 1 Bottle, Nalgene, 500ml $2.67 _____ _____ 6 Stirring rods, 6 ″ $1.66 _____ _____ 1 Bottle, wash, 250ml $4.14 _____ _____ 1 Stopp er, #4, 1 - hole, split $0.78 _____ _____ 1 Brush, test tube, 8 ″ $2.66 _____ _____ 1 Support, test tube $10.90 _____ _____ 1 Brush, test tube, 10 1/2 ″ $4.40 _____ _____ 12 Test tubes, 10mm × 75mm (3 ″ ) $0.44 _____ _____ 1 Bulb, 30ml, rubber $15.81 _____ _____ 6 Test tubes, 16mm × 150mm (6 ″ ) $0.63 _____ _____ 1 Clamp, pinch $4.58 _____ _____ 2 Test tubes, 25mm × 200mm (8 ″ ) $1.21 _____ _____ 1 Clamp, test tube $5.80 _____ _____ 1 Wire gauze, 6 ″ × 6 ″ cera mic $1.68 _____ _____ 1 Cylinder, graduated, 10ml $10.01 _____ _____ 1 Clay triangle $1.98 _____ _____ 1 Cylinder, graduated, 100ml $16.03 _____ _____ 1 Tongs, nickel - plated $15.46 _____ _____ 1 Flask, Erlenmeyer, 125ml $4.69 _____ _____ 2 Watch glasses, 50mm $4.05 _____ _____ 1 Flask, Erlenmeyer, 250ml $4.69 _____ _____ 1 Stir bar $3.55 _____ _____ 1 Funnel, glass, 65mm lg $9.76 _____ _____ 1 Thermometer $17.51 Lost or broken items should be replaced promptly. The above items were received in good condition, as verified by signature below. I understand that these items are solely my responsibility and that I must return everything I receive, also in good condition. Checked - in by____________________________________________Date checked - in__________________________ Student Signature TA Signature _____________________________________________Date __________________________

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    vii Instructor’s Equipment List Large Equipment Cathode ray tube with power supply 1 per group Capacitor setup (if not included with cathode ray tube) 1 per group Commercial apparatus for Millikan oil drop 1 per group Spectroscope 1 per group Hydrogen lamp 1 per group Mercury - vapor lamp 1 per group Power supply for lamp 1 per group Spectrometers 1 per group Centrifuges (addition test tubes) 1 per group Oven with insulated gloves 4 - 5 per room Geiger counter 1 per group Ring s tands with ring and clamp 1 per student Balances 4 - 5 per room Bunsen burners with lighter 1 per student Magnetic stirrer/hot plate 1 per 2 - 4 students pH meter and buffers 1 per 3 - 5 students Gel electrophoresis apparatus 1 per group Hot plate/stirrers 1 per group UV transilluminator and camera Section Equipment 50 mL buret 1 per student Buret clamp 1 per student Filter flask 1 or more per group Buchner f unnels 1 or more per group Porcelain crucible and cover 1 per student Shooting mechanism 1 per group Compass or string 1 per group 10 - 15 mL plastic centrifuge tube with cap 1 per group Bar magnet 4 - 5 per room Crystallization dish 1 per student Ruler (in cm) 1 per student 1000 - mL or larger beaker 1 per group 3 - L or larger graduated cylinder 1 per section 2 - L or larger graduated cylinder 1 per section 100 - mL graduated cylinder 1 per group 25 - mL graduated cylinder 1 per student or group 20 - L or larger bucket 1 - 2 per section 40 feet tygon tubing – ¼ inch diameter 1 - 2 per section Stopper (size 000) 1 - 2 per section Meter stick or tape measurer 1 per group #9 rubber stopper 1 per group

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    viii Styrofoam cup 2 per student Lid for cup (with hole for thermometer) * 1 per student 500 - mL Erlenmeyer flask 2 per student or group 125 - mL Erlenmeyer flask 6 per group Backdrop material (aluminum foil, etc.) Spray bottles 5 - 6 per section Molecular model kit 1 per student Paint brushes 1 per group Plastic baby doll 1 per group Heat gun 1 - 2 per group Cotton broad cloth 1 - 2 yards per group Knife 1 or more 5 - 6 all - purpose lighters (Aim - N - Flame) Crystallization dish 800 mL or 1 L beaker 1 per student Pencil Black light (optional) Scissors 1 - mL pipet 1 per student 2 - mL pipet 1 per student 5 - mL pipet 1 per student C uvette (if required for spectrometer) 1 per student White cloth cut into squares 1 yard per class Alpha, beta, and gamma sources 1 per group Piece of paper 1 per group Piece of wood, ~1/4 inch thick 1 per group Sheet of lead, ~1mm thick 1 per group Thicker piece of lead 1 per group Cobalt (blue) glass plates >2 per room Stopwatch or timer 4 - 5 per room Plexiglass box 13 ″ × 13 ″ × 13 ″ 1 per group Styrofoam balls 2 3/8 ″ > 23 per group Target marbles > 60 per group Jumbo marbles > 60 per group Play balls 2.4 ′ or 60 mm > 90 per group Consumable materials Filter paper Food coloring Marking pen Weight boats (capable of holding 8 mL water) Boiling chips Laboratory soap 9 ″ Pasteur pipet Pasteur pipet bulb Balloons (7 ″ round)

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    ix Rubber bands Tooth picks (plastic, round) Plastic wrap (parafilm or aluminum foil) Tape or staples/stapler Nichrome wire Candy pieces Chalk Ink Meat drippings Diet Coke (2 L bottles) Mentos pUC19 plasmid DNA solution 1 mL or similar - size microcentrifuge tubes Alka Seltzer tablets Ice Tap water Instructor’s Chemical List (note for section of 24 students) 3,3’,5,5’ - tetramethylbenzidine solution <100 mL 4 - (2 - pyridylazo)resorcinol, monosodium salt hydrate <0.1 g 9,10 - Bis(phenylethynyl)anthracene 0.12 g 9,10 - Diphenylanthracene 0.12 g Acetic acid 30 mL Acetone 1.0 L Agerose ( g el quality) 10 g Aluminum foil 3 rolls Aluminum hydroxide 5 g Ammonia - based cleaning solution or 6M NH 4 OH ~1 L Ammonium acetate 80 mL Ammonium carbonate monohydrate 6.0 g Ammonium hydroxide <3 L Ammonium oxalate <50 mL Ammonium sulfate <50 mL Ascorbic acid 10 g Barium chloride 30 mL Barium n itrate 5 g Benzene 300 mL Benzyl alcohol <100 mL Bromophenol blue <20 mL Butyric acid <200 mL Cadmium ~1 kg Calcium chloride 30 mL Calcium sulfate 30 mL

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    x Chloroform 500 mL Chromium ~1 kg Chromium chloride hexahydrate <30 g Cobalt chloride hexahydrate <50 g Concentrated Hydrochloric acid 1 - 2 L Concentrated Nitric acid 1 - 2 L Concentrated (NH 4 ) 2 S x 80 mL Concentrated Sulfuric acid 1 - 2 L Copper (II) chloride 50.0 g Copper sulfate pentahydrate <30 g Copper wire 12 g Corn starch ~50 g Dichloromethane < 3 L Diethylenetriamine <1 L Ethanol 2 L Ethidium bromide <0.1g Ethylenediamine <1 L EDTA 1 g FD&C #2, indigo carmine 5 mg FD&C Red #40 <0.1 g Ferric oxide powder ~500 g Fluorescein 1.2 g Formic acid <100 mL Glacial acetic acid 50 mL Glycerin < 10 mL Hexanol <100 mL Hydrogen peroxide <200 mL Iron ~1 kg Iron (III) nitrate (prepare fresh) 30 mL Iron filings <10 g Iron fillings 2.500 g Iron s ulfate (prepare fresh) 5 g Isoamyl alcohol <100 mL Isobutyl alcohol <100 mL KHP (potassium hydrogen phthalate) 50 g Lemon juice ~500 mL Leucomalachite green solution <100 mL Lithium chloride 10.0 g Lithium metal 5 g Lithium nitrate 5 g Luminol (3 - aminophthalhydrazine) 2.4 g

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    xi Magnesium chloride 5 g Magnesium hydroxide 5 g Magnesium sulfate 25 g Malonic acid 100 g Manganese ~1 kg Mercurous chloride <5 mL Methanol 7 L Methyl red <0.1 g Methyl salicylate <5 mL Methyl violet in dropper bottle 20 mL Methylene chloride 30 mL Naphthalene <300 g Nickle sulfate septahydrate 70 g Octanol <100 mL Oleic acid 0.02 g Oxalyl chloride in dichloromethane <100 mL Para nitrophenyl phosphate, disodium salt hexahydrate 25 mL para - dichlorobenzene 25 g Picolinic acid 1 g Phenolphthalein 1 L Potassium bromate 100 g Potassium chloride 5 g Potassium dichromate <10 mL Potassium ferrocyanide <10 mL Potassium metal 5 g Potassium nitrate 300 g Potassium permanganate 30 mL Potassium thiocyanate <15 mL Propanol <100 mL Propionic acid <100 mL Prostatic acid phosphatase (bovine) 25 mL Red #40 0.125 g Rhodamine B 1.2 g Salicylic acid 50 g Saturated b arium hydroxide <50 mL Saturated M s ilver nitrate <125 mL Silver sulfate <10 g Sodium acetate <2 g Sodium bicarbonate 300 g Sodium bismuthate 15 g Sodium carbonate 48.0 g

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    xii Sodium citrate 5 g Sodium chloride 50.0 g Sodium hydrogen carbonate 5 g Sodium hydrogen phosphate <5 mL Sodium hydroxide 5 - 6 L Sodium hypochlorite 30 mL Sodium metal 5 g Sodium nitrate 5 g Stearic acid 5 g Strontium chloride 10 g Sucrose 10 g Thioacetamide 410 g Tin 10 g Tin chloride ~1 kg TRIS - acetate 1 g Xylene cyanol FF 1 g Zinc 2.5 g Zinc oxide ~1 kg

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    1 Experiment 1 Laboratory B asics: Accuracy and P recision – Who’s the S hooting C hampion ? For the I nstructor This lab is designed to add fun and excitement to the traditional first experiment in the first - semester general chemistry laboratory. For shooting at a target, we would recommend being open to experimentation. A large catapult throwing water balloons at a large target such as a sheet painted with a bull’s eye, a paint ball gun and target, blunt - tipped arrows shot into a target mounted on a thin piece of styrofoam, throwing horseshoes, rolling balls into a bull’s eye, throwing small bean bags (as in tail gate toss) at a target, chipping golf balls at a flag, or even just darts and a dart board can be considered. A safe indoor alternative is foam dart guns; these darts can be fired at a target drawn on a dry erase board or chalk board. Cost is only around $10, and they can be found at most toy stores. Moistening the end of the suction cups helps the dart to adhere to the target. In our experience, 10 mL disposable plastic centrifuge tubes are surprisingly accurate, just as accurate within error as 10 mL graduated cylinders. However, because the tubes have fewer graduations, estimating the last significant figure when adding a given mass of water is more difficult. We have also found that the reproducibility of measuring 8 mL of water is greater with the plastic tubes compared to the graduated cylinder as it is easier in the plastic to gently tape the container to remove air bubbles and water droplets clinging to the side. Preparation Information – 24 students Shooting mechanism (refer to previous discussion) 1 per group Compass or string 10 - or 15 - mL plastic centrifuge tube with cap 1 per group Weight boats (capable of holding 8 mL water) 1 per group Necessary Equipment – 24 students Paper towels Disposable gloves Balance 4 or 5 per room 10 - mL graduated cylinder 1 per group

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    Experiment 1: Laboratory Basics: Accuracy and Precision – Who’s the Shooting Champion? 2 Answers to Pre - Laboratory Questions 1. William Tell had only one shot to shoot an apple from the top of his son’s head with his bow and arrow. If you were William Tell and you loved your son, would you rather be accurate or precise? Explain why. Accurate – hit the apple. Precise refers to reproducibility, which is not applicable with one shot. 2. Assume that you found that the average volume of water required to fill the graduated cylinder to the 8.00 mL mark was 7.95 mL. Calculate the % error. (7.95 mL − 8.00 mL)/8.00 mL × 100% = 6%

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    3 Experiment 2 Components of a Mixture – What I s T hat S tuff in the B ottom of the C ereal B ox? For the I nstructor The mixture per student should contain approximately 5 mg red #40, 100 mg Fe, 100 mg ZnO, 200 mg stearic acid, and 395 mg sucrose per gram. If the sucrose crystals are large, they might take a considerable time to dissolve , and grinding the sucrose before making the mixture is advisable. The concentration of the methanol solution from 200 to 5 - 10 mL will take longer than a single lab period. This process can be facilitated by placing in a well - ventilated hood. During the following week, someone will need to check these and move them to a freezer at the appropriate time. Very little time will be required during the next laboratory period to complete the experiment. This experiment can be performed much faster if gravity filtration is replaced with the use of a Buchner funnel, filter flask, and vacuum source. Preparation Information – 24 students Methanol ~6 L Chloroform <500 mL (mixture – 25 g) ~25 g per section Iron fillings 2.500 grams Zinc oxide 2.500 grams Sucrose 9.875 grams Red #40 0.125 grams Stearic acid 5.000 grams Necessary Equipment – 24 students Paper towels Disposable gloves Filter paper Weigh boats/weighing paper Funnel 1 per student Beaker (20 mL) 2 per student Beaker (400 mL) 2 per student 10 - mL graduated cylinder 1 per student (optional) 100 - mL graduated cylinder 1 per student (optional) Ring stand 1 per student Iron ring 1 per student

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    Experiment 2: Components of a Mixture – What Is That Stuff in the Bottom of the Cereal Box? 4 Clay triangle 1 per student Stirring rod 1 per student Wash bottle 2 per 1 - 4 students Spatula 1 per student Bar magnet 1 per 1 - 4 students Rubber policeman 1 per student Magnetic stirrer/hot plate 1 per 2 - 4 students (optional) Balance 4 - 5 per room Answers to Pre - Laboratory Questions 1. How could you determine (without tasting) whether a container of a colorless liquid contained ethanol or ethanol and sucrose? Allow the ethanol to evaporate ; a white crystalli ne solid left would indicate the presence of sucrose. 2. Does this experiment demonstrate the law of conservation of matter? No. No chemical reactions are involved, only physical separations. 3. Explain the difference between filtration and decantation (see the “Experiment E quipment and P rocedures” section of this manual). Why might one want to use filtration in this experiment rather than decantation? Decanting works if solid(s) stay at the bottom of the container. If they are likely to be disturbed, then filtration should be used. 4. How could one rapidly separate red #40 from zinc oxide? Indicate every step. Add water and agitate to dissolve the red #40. Filter and wash the solid with water. Solid remaining is zinc oxide. 5. Separation techniques are pe r formed on a sample containing sand and salt. It was determined that there were 5.43 g of sand and 4.52 g of salt. The total sample weight was 10.50 g. What is the percent recovery of sand from the sample? (5.43 g + 4.52 g)/10.50 g  100% = 94.8%

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    5 Experiment 3 Cathode Ray Tubes, Millikan Oil Drop, and Avogadro’s Number For the I nstructor We believe it is very important that students actually measure a fundamental constant or another important number used in general chemistry lecture s . Given the emphasis placed on the charge on an electron in most general chemistry textbooks, this is our fundamental constant of choice. Unfortunately, this determination cannot be performed with normal general chemistry laboratory equipment; in fact , the equipment is rather expensive compared to most general chemistry equipment. If we had ideal conditions and budgets, we would have students measure the charge to mass ratio on an electron using a commercial system sold by Pasco ( www.pasco.com ) and then use a commercial system to perform the Millikan oil drop experiment (also sold by Pasco and other companies); however, the apparatuses cost $1,500 to $2,500. Students can more affordably look at the behavior of electrons in cathode ray tubes ($500 - $1,000 for a commercial setup and power supply, available from many science education equipment suppliers). We particularly like the cathode ray tubes with electrodes for applying a magnetic field built in (at the time of writing, ~$250 from Sci - Supply plus the cost of a power supply). An alternative is to use an oscilloscope, as it contains a cathode ray tube. Instructors may already possess one in their department or be able to borrow one from their institution’s electrician or physics department. In addition to deflecting the path of the electrons of a cathode ray tube with magnets, the path can be altered by applying an electric field with a capacitor (if one is not built into the unit); these are also available ( < $500 plus power supply) from many science education equipment suppliers. This again is not an insignificant cost, while one might be able to borrow these from a neighboring physics department. Fortunately, obtaining a reasonable value for Avogadro’s number can be accomplished cheaply and easily in a time - tested experiment. This can also be performed as a demonstration by placing the watch glass on an overhead projector. To form a monolayer requires only a few drops of the oleic acid solution. If students use more than 20 drops, they are probably forming multiple layers. Also, in our experience, students should be walked through the calculations in a lecture.

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    Experiment 3 : Cathode Ray Tubes, Millikan Oil Drop, and Avogadro’s Number 6 Cathode ray tube Preparation Information – 24 students Cathode ray tube with power supply 1 per group Bar magnets >1 per group Capacitor setup (if not included with cathode ray tube) 1 per group Millikan oil drop Preparation Information – 24 students Commercial apparatus 1 per group Avogadro’s Number (24 students) Benzene is a possible carcinogen. Benzene - containing solution must not be disposed of down the drain. The oleic acid/benzene solution should have a concentration of 0.02 g oleic acid per L solution. The methyl violet solution should be about 0.5%. A class of 24 should need ~0.5 L of oleic acid/benzene solution, <250 mL benezene, and <20 mL of 0.5% methyl violet solution per class of 24. Placing the ammonia - based cleaning solution in a wash bottle for students to use is recommended; the glassware is easier to clean in this manner, while the students use less of the solution. A pipetter tha t dispenses a volume of 10  L could be use d to replace the Pasteur pipet and calibration process. Preparation Information – 24 students Oleic acid 0.02 g for solution Benzene 300 mL Methyl violet solution in dropping bottle 20 mL Ammonia - based cleaning solution or 6 M N H 4 OH ~1 L Deionized or distilled water Laboratory soap Necessary Equipment – 24 students 9 ″ Pasteur pipet 2 per student Pasteur pipet bulb 1 per student 4 - inch watch glass 1 pert student Dropping bottle 1 per class 10 mL beaker 1 per student 5 - or 10 - mL graduated cylinder or 1 - mL volumetric tube 1 per student Ruler (in cm) 1 per 4 - 6 students Paper towels Disposable gloves

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    Experiment 3 : Cathode Ray Tubes, Millikan Oil Drop, and Avogadro’s Number 7 Answers to Pre - Laboratory Questions 1. Oleic acid is a fatty acid and is essentially immiscible (insoluble in water). Given this, why do you think that the glass surfaces in this experiment must be cleaned so carefully? Oleic acid may interact and stick to oil residue on glass surface rather than form layer on top of water. 2. Find a material safety data sheet (MSDS) for benzene on the Internet. What are the hazards associated with working with benzene? What precautions should be taken? A Google search of “MSDS benzene” will provide many examples. Hazards include carcinogenic, possibly mutagenic, and developmental toxin s . Wear splash goggles, lab coat, and gloves.

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    8 Experiment 4 Conservation of Mass and Reaction Types – Copper Recovery Cycle For the I nstructor This is a very conventional experiment, found in many laboratory books. This is because it is straightforward and directly illustrates concepts from the textbook. In other words, it works and illustrates concepts well; thus, students like it, and therefore we like it. Students should be warned about handing strong acids (HNO 3 and H 2 SO 4 ) and bases (NaOH). Copper - containing solutions (as with all solutions containing transition metals) should not be disposed of down the sink. This lab can be longer than the normal 2½ - to 3 - hour laboratory session , although we have had the students complete the experiment in 2½ hours. The experiment may be stopped after any of the steps. The solutions or solids need only be covered and saved until the next session. If the necessary equipment is available, time can be saved by having the students use two filtration setups. Preparation Information – 24 students Aluminum foil Copper wire 12 g (0.5 g per student) Conc. Nitric Acid 240 mL Conc. Hydrochloric Acid 24 mL 3.0 M NaOH 1 L 6 M Sulfuric Acid 360 mL Methanol 120 mL Acetone 120 mL Necessary Equipment – 24 students Paper towels Disposable gloves Red Litmus paper Boiling chips 2 - 3 per student Filter paper Weigh boats or weighing paper Bunsen burner 1 per student Evaporating dish 1 per student Wire triangle 1 per student Funnel 1 per student 10 - mL graduated cylinder 1 per student 100 - mL graduated cylinder 1 per student 250 - mL Erlenmeyer flask 2 per student 250 - mL beaker 2 per student

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    Experiment 4: Conservation of Mass and Reaction Types – Copper Recovery Cycle 9 Beaker to use with evaporating dish to make steam bath Stirring rod 1 per student Ring stand and iron ring 1 per student Wire gauze 1 set per student Rubber policeman 1 per student Hot plates (optional) 1 per student Balance 4 or 5 per room Answers to Pre - Laboratory Questions 1. List the hazards involved in this experiment. What can you do to minimize the chan c es of anything bad happening in each case? Sulfuric acid and nitric acid are strong acids, while sodium hydroxide is a strong base. Be careful and wear gloves and goggles; lab coats are a good suggestion. Immediately wash any skin or clothing that comes in contact. Wash surfaces that come in contact so that someone else is not exposed accidentally. Have appropriate spill kits nearby. 2. Name the gas produced when nitric acid is added to copper metal. Nitrogen dioxide 3. During your experiment, you use 0.597 g of copper to start your reaction. After you carry through all the different steps, you recover 0.684 g of copper. What is the percent recovery of copper? Since it appears that you may have created matter (which is not possible in this experiment), what could be a source of error? (0.597 g – 0.684 g)/0.597 g  100% = 146%. Solid not properly dried is most obvious possibility. 4. Identify the reaction types in equations 1, 2, 4, and 5. Indicate why you made these choices (e.g., indicate gaseous products, precipitates, etc.). Eqn. 1 – gas forming – NO 2 (g). Also redox – Cu 0 → Cu 2+ ; N +5 → N +4 Eqn. 2 – precipitation – Cu(OH) 2 (s) Eqn. 4 – acid base – O 2 − + 2H + → H 2 O Eqn. 5 – redox – Cu 2+ → Cu 0 ; Al 0 → Al 3+

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    10 Experiment 5 Equivalent Weights and the Periodic Table For the I nstructor Students should be instructed about the concerns associated with the use of corrosive materials. Students may desire to wear gloves. The aqueous solutions resulting from filtering and washing the unreacted metals are not suitable to be poured down the drain. The solution for each metal should be placed in a separate labeled waste container. Helium quality balloons should be used. The quality of the balloons used i s important. If helium quality balloons are not used, the highest quality available should be used. If lower quality balloons are used, then the time used to collect the hydrogen gas should be minimized to prevent gas loss. This experiment is best performed over three weeks. At the end of lab 4 (or whatever lab is performed before this one), students should go ahead and label everything, weigh out the metal samples, and place them into the appropriate balloons. This way the next week the acid can be placed in the tubes and the metal added early in the lab period to maximize the time for Fe, Mn, and Cr to react with the acid. The third week the Cd, Zn, and Sn portion can be completed. If the reactions with Zn, Cd, and Zn go to completion well before the third laboratory period, someone should measure the volume of the balloons promptly. This is preferably done after one day. If necessary, the reactions can be terminated at the same time as those of Fe, Mn, and Cr; the volume and mass changes will just be small. The results of this experiment are designed to be used in conjunction with those of experiment 8. Preparation Information – 24 students Manganese 24 g Chromium 24 g Iron 24 g Zinc 24 g Cadmium 36 g Tin 36 g Concentrated hydrochloric acid 300 mL Ethanol 500 mL Necessary Equipment – 24 students Weigh boats Paper towels Marking pen Filter paper 1000 - mL or larger beaker 1 per group Test tubes (15 mm × 150 mm) 6 per group

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    Experiment 5: Equivalent Weights and the Periodic Table 11 Balloons (7 ″ round) 7 per group Test - tube rack 1 per group Rubber bands up to 6 per group Filter flask 1 or more per group Buchner Funnels 1 or more per group Wash bottle 2 per group Spatula 1 or more per group Test - tube holder 1 or more per group Hot plate 1 per group 3 L or larger graduated cylinder 1 per lab section Balances 4 - 5 per room Answers to Pre - Laboratory Questions 1. What is th e valence for the six metals based on their reaction with hydrochloric acid? Cr − 3 Mn − 2 Fe − 2 Zn − 2 Cd − 2 Sn − 2 2. How are atomic weights determined experimentally at the current time? Mass spectrometry is the most obvious answer from freshman textbooks. 3. What safety precautions are necessary in this experiment? Hydrochloric acid is a strong acid. Be careful and wear gloves and goggles; lab coats are a good suggestion. Immediately wash any skin or clothing that comes in contact. Wash surfaces that come in contact so that someone else is not exposed accidentally. Have appropriate spill kit nearby.

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    12 Experiment 6 Hydrates For the I nstructor Concentrated nitric acid (~15 M) should be carefully diluted in 2.5 fold to give ~6 M HNO 3 . Preparation Information − 24 students CoCl 2 · 6H 2 O <30 g CuSO 4 · 5H 2 O <30 g CrCl 3 · 6H 2 O <30 g 6 M nitric aci d <2 L Necessary Equipment – 24 students Paper towels Disposable gloves Large beaker for acid bath 1 or more per class Porcelain crucible and cover 1 per student Crucible tongs 1 per student Ring stand with ring 1 per student Clay triangle 1 per student Pasteur pipet and bulb or dropper 1 per student Blue litmus paper 1 piece per student Bunsen burner 1 per student Lighter for burner 1 per 1 - 4 students Analytical balance (4 decimal places) 4 - 5 per room Answers to Pre - Laboratory Questions 1. If a hydrate of the formula MCl y · xH 2 O decomposes when heated to produce HCl, what change would you expect to occur when a piece of blue litmus paper is held in the path of the vapor released? Explain. The blue litmus paper should turn red as blue litmus paper turns red in the presence of acid and HCl is hydrochloric acid.

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    Experiment 6: Hydrates 13 2. After 0.6523 g of CoCl 2 · 6H 2 O is heated, the residue has a mass of 0.3423 g. Calculate the % H 2 O in the hydrate. What is the formula of the hyd rate? 0.6523 g total − 0.3423 g CoCl 2 = 0.3100 g H 2 O 0.3100 g H 2 O/0.6523 g total × 100% = 47.52 % H 2 O 0.3100 g H 2 O/18.02 g · mol − 1 = 0.01720 mol H 2 O 0.3423 g CoCl 2 /129.83 g · mol − 1 = 0.002637 mol CoCl 2 0.01720 mol H 2 O/0.002637 mol CoCl 2 = 6.523 Formula is approx. CoCl 2 · 6.5 H 2 O 3. What safety precautions are necessary in this experiment? Nitric acid is a strong acid. Be careful and wear gloves and goggles; lab coats are a good suggestion. Immediately wash any skin or clothing that comes in contact. Wash surfaces that come in contact so that someone else is not exposed accidentally. Have appropriate spill kit nearby. 4. CoCl 2 is often used in hygrometers. Search the Internet to determine why. How does this relate to this experiment? Hygrometer indicates relative humidity, CoCl 2 is blue. As it picks up water, it forms CoCl 2 · 6H 2 O which is pink. See , for example , http://wow.osu.edu/experiments/weather/humiditymonitor.html .

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    14 Experiment 7 Gas Laws For the Instructor Note that you will need to find an appropriate space in your facility (balcony, stairwell, etc.) where one can make a measurement at the appropriate height (between 30 and 40 feet). The tygon tubing can be sealed at one end by plugging with a rubber stopper. We have used filling the tubing as an inquiry - based exercise; thus, the procedure for this experiment is not spelled out in the lab procedure for the students. Many groups independently find our best solution – a pipet bulb can be used to set up a siphon, pulling water from the bucket through the tubing, followed by sealing the end quickly. The filled tubing should be kept in the bucket to prevent air from getting in until the barometer reading is attempted. The local barometric pressure can be obtained from any number of sources. For example, a convenient source is www.weatherchannel.com ; just enter a zip code. For the second part of the experiment, we have found that drivin g a nail half way through the #9 rubber stopper and then removing it makes a hole suitable to insert the syringe and get an excellent seal. The holes should be made in advance, not by the students in the lab, to avoid getting smashed fingers. The syringe should have a Luer - slip tip. Necessary Equipment – 24 student 20 - L or larger bucket 1 - 2 40 feet tygon tubing – ¼ inch diameter 1 - 2 Stopper (size 000) 1 - 2 Food coloring Meter stick or tape measurer 1 per group Pipet bulb 1 per group Ring stand 1 per group Clamp 1 per group 50 - mL plastic syringe 1 per group #9 rubber stopper 1 per group Glycerin Textbooks 4 per group Balance (capable of measuring kg quantities) 1

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    Experiment 7: Gas Laws 15 Answers to Pre - Laboratory Questions 1. Look up the atmospheric (or barometric pressure) in your area in the newspaper, on television, or another news outlet. What are the units used? Convert to mm Hg. Convert to mm H 2 O. 30.07 inches Hg  2.54 cm/in  10 mm/cm = 762 mm Hg 762 mm Hg  13. 5340 g · ml − 1 /0.99707 g · ml − 1 = 1.03  10 4 mm H 2 O 2. Should atmospheric pressure increase or decrease as one goes from the beach to the mountains? Explain. Decrease, as less of the earth’s atmosphere above. 3. If the column of water in the water barome ter rose to a height of 35 feet, what would the atmospheric pressure be in mmHg? 35 ft  12 in/ft  2.54 cm/in  10 mm/cm = 1.1  10 4 mm water 1.1  10 4 mm  0.99707 g · ml − 1 / 13.5340 g · ml − 1 = 8.1  10 2 mm Hg 4. After you set up your apparatus for par t two of the experiment , your group begins to add the textbooks to the plunger. It appears that the plunger continues to drop with every added book and does not return to its original place after the books are removed. What could be possible sources of error for this experimental reaction? Be specific and give at least two possible reasons. 1) Syringe is leaking – make sure firm seal with tip in stopper and piston in syringe 2) Piston not sliding freely – lubricate as described.

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    16 Experiment 8 Styrofoam Cup Calorimetry: Atomic Weights For the instructor The results of this experiment are designed to be used in conjunction with those of experiment 5. The experiment can be performed individually; or to reduce time, samples of the metals can be divided among members of groups. Normally, individuals or groups can each only make measurements on at most three metals in a single lab period. A paper towel, folded to make it thicker, can be placed around the thermometer at the point where it is clamped to help keep the thermometer in place by the clamp; we find this preferable to a one - hole rubber stopper (as students often snap off thermometers attempting to insert them into rubber stoppers). The thermometer is clamped in place primarily to keep it from tipping over the calorimeter. If a stirring bar is used, the thermometer should be placed off center, leaving room for the stir bar to turn. Preparation Information – 24 students The mass of the metal pieces should be approximately 3 - 5 grams. Manganese ~1 kg Chromium ~1 kg Iron ~1 kg Zinc ~1 kg Cadmium ~1 kg Tin ~1 kg Necessary Equipment – 24 students Weigh boats Paper towels Styrofoam cup 2 per person Lid for cup (with hole for thermometer) * 1 per person Thermometer 2 per person Ring stand 1 per person Utility clamp 1 per person Metal wire or stirring bar 1 per person Magnetic stirrer 1 per person (optional) 400 - mL beaker 1 per person 250 - mL beaker 1 per person Tongs 1 per person 100 - mL graduated cylinder 1 per person Test tube 1 per person Test tube holder 1 per person Balances 4 - 5 per room * A second tiny hole will be needed if stirring is done with a piece of wire.

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    Experiment 8: Styrofoam Cup Calorimetry: Atomic We ights 17 Answers to Pre - Laboratory Questions 1. Find and report literature values for the specific heats of the metals used in this e xperiment at room temperature. Cr – 0.107 cal · g − 1 · K − 1 Mn – 0.114 Fe – 0.106 Zn – 0.092 Cd – 0.0555 Sn – 0.053 From Chemical Rubber Handbook 2. Compare the specific heats of the metals with their atomic weights (i.e., molar masses). Do you see any tre nds? Make a plot to show this relationship. What does the plot reveal? Inversely related. Slope is negative of constant of E qn. 1. For this plot of these few metals, the value is ~8.7. Atomic Weight 40 60 80 100 120 140 specific heat 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12

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    Experiment 8: Styrofoam Cup Calorimetry: Atomic Weights 18 3. If you are performing the calibration step of this experiment and you begin with 50 g of water at 20 °C and 50 g of water at 80 °C. After adding the two in your calorimeter setup and following the procedure outlined in the experiment, you determine the temperature of the mixed so lutions to be 45 °C. What is the heat capacity of the calorimeter? Use Eqn. 4 and assume room temperature is 25 ° C: - S.H. warm water  mass warm water   T warm water = S.H. cool water × mass cool water   T cool water + C calorimeter   T calorimeter - 1.00 cal/g · K  50 g  (45 ° C − 80 ° C) = 1.00 cal/g · K  50 g  (45 ° C − 20 ° C) + C calorimeter  (45 ° C − 25 ° C) C calorimeter = 25 cal/K

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