CHEM 1200 Student Assessment PDF

# Student Assessment ## Final grade calculation: - 1% Skill Development Exercise - 20% Online pre-lab assignments (15 in total, equally weighted) - 10% Laboratory work practical mark - 20% Lab Reports (5 in total, equally weighted) - 40% Final Exam ## Skill development exercise - First day in the...

# Student Assessment ## Final grade calculation: - 1% Skill Development Exercise - 20% Online pre-lab assignments (15 in total, equally weighted) - 10% Laboratory work practical mark - 20% Lab Reports (5 in total, equally weighted) - 40% Final Exam ## Skill development exercise - First day in the lab - 1% of total grade On your first day in the laboratory, you will perform a skill development exercise. This activity will give hands-on experience with common glassware and equipment used this term and allow you to familiarize yourself with the layout of the laboratory. You will review and perform some basic laboratory techniques and fill in an answer sheet of your results. This exercise is completed independently (not with a partner) and is a chance to assess your readiness to work in the lab. Take advantage of the resources available to you during the lab course materials, handouts, your lab manual, TAs, lab instructor, etc. If something is new or unfamiliar, ask questions! No preparation is required for this exercise, everything you need will be available in the lab. But, if you love science and learning as much as we do, and want to spend some time reviewing techniques, you'll find lots of information on Waterloo LEARN - CHEM 1200 - Content - Techniques and Lab Technique Videos, or in Appendix C of this manual. ## Laboratory performance mark - 10% of total grade Each day as you work in the lab your TA will be assessing your performance, evaluating things like punctuality, preparedness, safe lab practices, work ethic, technique and attitude. At the end of each day, the cleanliness of the laboratory room is assessed. If spills in the public spaces (balances, fume hoods, chemical dispensing benches, etc.) are not cleaned up correctly, that lab section loses a lab performance mark. When assigning lab performance marks, here are some things TAs consider: Did you: - Arrive on time, well prepared for the work? - Make efficient use of lab time? - Follow safety rules? - Wear safety goggles at all times? (-1 mark each time you are observed without your goggles) - Share the workload equally with your partner? - Maintain a positive attitude? - Clean your workspace at the end of the day? ## Pre-laboratory tasks ### Pre-lab Task 1: Pre-lab assignments (PLIs) - 20% of total grade Before each experiment you will complete an online pre-lab assignment (follow the link from Waterloo LEARN - CHEM 1200) on the material you need to know for the upcoming experiment. Questions address the techniques, safety guidelines and background information and review some of the calculations needed for the report. Pre-lab assignments are activated exactly 7 days prior to your scheduled laboratory period and access is time restricted. You must complete the assignment at least 24 hours before your scheduled lab period. During the six days your assignment is active you can work on the assignment as much as you like, but you can only make one submission. Pre-lab assignments are one attempt only, do not submit the assignment until you are ready to have it graded. ### Pre-lab Task 2: Experimental Procedure Summary (EPS) - 10% of each report grade Before you begin your work in the lab you are required to submit an experimental procedure summary (EPS) to your Teaching Assistant (TA). It will be notarized and returned to you. This summary must be handwritten, not computer generated or copied. The EPS should contain all the information necessary to perform the experiment in the absence of your lab manual, and it will be graded as part of the lab report mark for that experiment. The choice of format is up to you, point form, flow charts, diagrams, etc., are all acceptable. Sample formats can be found on Waterloo LEARN - CHEM 1200. ### Pre-lab reports - 20% of total grade For each experiment in CHEM 1200, you will be required to prepare a post-lab report for grading. Reports are equally weighted, each contributing 5.8% toward your final grade. Different types of reports are required for different experiments, in each case the required report type is specified on the first page of the experiment background. For complete information on types of reports required in this course see Appendix A of this lab manual. ### Final exam - 40% of total grade A written final exam is held in this course, during the exam period at the end of the term. This exam is scheduled by the Registrar, the date, time and location information will be published on the "Schedule of Exams" released in October. The exam covers all material presented in the course over the entire term. To earn credit for CHEM 1201, you must write this exam. More information regarding the format and content of the exam will be shared during the term. # Academic Integrity The University of Waterloo has identified six core values which support academic integrity at Waterloo: honesty, trust, fairness, respect, responsibility and courage. Your instructors trust that you will engage in their courses and programs with your best intentions to learn, grow and to reach future career goals. We also understand that grades are an important currency to students and that students often feel pressure to earn high grades to achieve their goals. Conversely, instructors see grades as a reflection of student knowledge and understanding and require them to be an honest means to differentiate ability. Instructors emphasize fairness by evaluating all students using the same criteria and demonstrate honesty by giving clear guidelines for assignments and reasonable feedback on student work. When you submit work for grading you are presenting it as your own, original work. Students who submit work that is not original are subject to disciplinary penalties under University of Waterloo Policy 71 which relates to academic misconduct. All cases of academic misconduct in CHEM 1200 are referred to the Associate Dean of your faculty. The Associate Deans are lovely people, but this is not the context in which you want to meet them. A typical penalty for academic misconduct is a grade of zero assigned to the related course element, plus a deduction of 5% of the course grade. ## Serious academic offences include, but are not limited to: ### Plagiarism: The words and ideas you submit must be your own. You will use many sources of information during your academic career, but these sources must be properly acknowledged using citations and references in your work. You must learn to present information you have researched in your own words. If you "cut and paste" directly from your source, the words are not yours, but those of the original author. Remember that even ideas that have been paraphrased must be referenced. ### Copying from another's work or allowing someone to copy your work: Copied lab reports will receive a mark of zero. No attempt is made to differentiate between the "copier" and the "copyee". Reports are to be written on an individual basis. No portion of your lab report should be the same as any other person's report. ### Use of unethical resources: It is often difficult for students to determine the validity of information, particularly in the online environment. Many online resources claim to give "expert" answers, provide full report writing services or copies of previous reports and assignments. Resources of this type (Chegg, CourseHero, etc) are predatory, they encourage you to compromise your own integrity by uploading instructor owned or confidential materials in exchange for access to what is very often questionable information of limited usefulness. ### Fabricating data: As future scientists, you know that making up data values is wrong. In this course, there are never penalties assigned for "bad" data, in fact, more is often learned by making some mistakes, recognizing them and explaining their effect on the experimental results. Always work with the data that you personally gather in the lab, unless a TA or instructor gives specific instructions otherwise. ## Use of AI authoring tools: The ability to effectively communicate scientific material is a skill that this course is attempting to instill in students. We recognize that there are a variety of AI programs available to you, but you must be aware that AI programs are not a replacement for human creativity, originality, and critical thinking. In specific circumstances, and with proper attribution, AI programs may be used as a tool in this course; speak to your instructor for more information before you use these tools. ## Academic Integrity: Information regarding academic integrity policies and offences can be found through the Office for Academic Integrity: https://uwaterloo.ca/academic-integrity. ## Grievance: A student who believes that a decision affecting his/her university life has been unfair or unreasonable may have grounds for initiating a grievance. Read Policy #70, Student Petitions and Grievances, Section 4. ## Discipline: You are expected to know what constitutes academic integrity, to avoid committing academic offenses, and to take responsibility for your actions. If you are unsure whether an action constitutes an offense or need help in learning how to avoid offenses (e.g., plagiarism, cheating) or about "rules" for group work collaboration, seek guidance from the course professor, academic advisor, or the Undergraduate Associate Dean. For information on categories of offenses and penalties, refer to Policy #71, Student Discipline. ## Appeals: Concerning a decision made under Policy #70 (Student Petitions and Grievances) (other than petitions) or Policy #71 (Student Discipline) a student may appeal the finding, the penalty, or both. If you believe you have grounds for an appeal, refer to Policy #72 (Student Appeals). # Where to Get Help When You Need It ## Looking for more information about this course? ### LEARN announcements: This course uses the Announcements widget on the Course Home page to communicate new or changing information as needed. You are expected to read the announcements on a regular basis. When something big is happening, you can find information in the course announcement. To ensure you are viewing the complete list of announcements, you may need to click Show All Announcements. ### Piazza discussion boards: This course uses Piazza as an anonymous discussion forum. Here you can post your questions to the class, to get timely help from your peers. Your TAs and instructor often monitor this site and can answer questions here as well. To enroll in the Piazza classroom, follow the link in the "Welcome Announcement" on LEARN. Note that discussions are organized by topics, make sure that your question is placed into the appropriate folder. Please check to see if your question has already been answered to avoid posting duplicate questions. You can edit questions as well if your question is like a question already posted. ### Your teaching assistant (TA): Your TA will be grading your lab reports, so questions about preparing reports, how reports are graded, etc., are best directed to your TA. TAs are also able to answer questions about course material or direct you to the appropriate spot if they don't know the answers They can be contacted using the "Connect" tab on our LEARN course. ### Course instructor: The best person to answer questions about special circumstances, that may affect your work in the course, absences, rescheduling or questions of a personal nature that you may not want to post on the discussion boards. Your instructor can also answer all your questions about the course material, course structure and policies. ## Technical support for course resources ### LEARN: For problems related to LEARN access or issues, refer "Request help" on the Mobius support page. ## Writing support for coursework ### The Writing Centre: Offers help with your writing skills. You can book an appointment with them or attend one of their Workshops or Writing Groups. A resource (prepared by people here at UW) for writing lab reports can be found here. # Safety in the Chemistry Laboratory ## Safety Orientation/WHMIS Online Course Before working in a Chemistry Laboratory at the University of Waterloo, you must have completed the Student Safety Orientation/ WHMIS at Waterloo online safety training course accessed via Waterloo LEARN. Complete this course by following the instructions here: https://uwaterloo.ca/safety-office/training/whmis-2015. When you have satisfactorily completed the WHMIS course, you will get a "Congratulations Your Name" certificate online, screen shot or print this certificate of completion and bring it with you to your first lab. You will be required to show your certificate of completion to your TA or lab instructor on your first day of CHEM 120L. If you cannot show proof that you have completed this course you will not be permitted to work in the laboratory. ## Protecting Yourself against Accidents/Injury ### Protective clothing: * **Lab Safety Goggles/Lab Safety Glasses:** Eye protection is mandatory for everyone in the first-year chemistry laboratory, goggles give maximum protection from spills and flying objects, but approved "shielded" or "close filed" safety glasses are also accepted. * **Footwear:** Shoes must fully cover the foot and provide slip resistance on wet floors (naming shoes are a good option). * **Lab Coats:** Students are strongly urged to buy a laboratory coat to protect your skin and clothing in this and subsequent years, however they are not mandatory. * **Long hair:** Must be securely tied back, ask for an elastic if you don't have one. * **Food and Drink**: Anything you plan to ingest should not be brought into the laboratory. Food or drink brought into the lab is no longer fit for human consumption and will be confiscated. ## Preventing Accidents/Injury Carefully follow all instructions (both written and verbal) and ask for clarification if you do not understand. Do not perform unauthorized experiments. Never leave an experiment unattended. Keep sinks and bench tops clean. Wipe up all spills and bottle rings immediately. Practice good housekeeping and clean up at the end of the period. This protects your skin and belongings from chemical contamination. Aisles and bench tops must be kept free of obstructions (knapsacks, books, bags, etc.) all personal belongings must be stored in the cubbies provided or under the bench. Become familiar with the chemicals you will be using before each experiment. Learn the safe handling and disposal requirements. Be aware of the potential for toxic vapors and gases to be produced and work in the fume hoods if necessary. When handling chemicals, keep hands away from the face, eyes and body until you have washed thoroughly. Wash often during the lab, and always wash your hands before you leave. Use proper equipment for each task and check that all equipment is in good working order before use. Work in fume hoods, use face shields and protective clothing where indicated. Watch for holes in burner tubing, melted or frayed electrical cords, etc. ## Treatment of Injury ### First Aid: In general, the best first aid for acid, alkali, or other chemicals splashed on the skin, cuts, abrasions or burns is immediate flushing with large quantities of tap water. Report accidents and injuries to your instructor or TA as soon as possible. This will ensure that proper first aid treatment is received. * **Chemicals on the skin:** If a chemical is splashed or spilled on skin, move to the nearest sink, eyewash or emergency shower and flush the affected area with large quantities of water. Inform your TA or instructor. If irritation or pain develops, report to Health Services. Be sure to bring all information pertaining to the chemical in question. * **Chemicals in the eye:** Locate the emergency eye wash nearest to your workstation. If a chemical enters the eye, flowing fresh water should be used immediately to flush out the eye for a minimum of 10 minutes. Have someone inform your instructor. After flushing, report immediately to Health Services. * **Cuts, abrasions and burns:** For treatment and dressing of cuts and burns, report to your instructor or TA. ## Additional Emergency Contact Information * **Major injury or illness:** * **Fire/Ambulance/Police:** Call 911 from any on campus phone * **Minor injury or illness:** * **Health Services:** 519-888-4096 or ex. 84096 * **UW Police (non-emergency):** 519-888-4911 or ex. 22222 * **Other health related concerns:** * **Poisoning/Overdose Information:** 1-800-268-9017 * **Telehealth Ontario (24-hour phone access):** 1-866-797-0000 # Fire and Explosions Fire is a significant hazard in the chemistry laboratory. To ensure the safety of everyone: * **Learn the location of the nearest fire exit, fire extinguisher, fire alarm pull station, emergency safety shower and fire blankets.** * **If the fire alarm sounds, turn off all services (gas, electricity, and water) and leave the building immediately via the exit indicated. Listen for additional instructions.** * **In the case of a fire or explosion in the lab, evacuate the room and close the doors. Pull the nearest wall alarm and leave the building immediately via the exit indicated. Avoid inhaling smoke and gases resulting from fire or explosion.** * **If clothing catches fire, stop where you are, drop to the floor and roll to smother the fire. DO NOT RUN.** * **Assemble apparatus so that control valves and switches will remain accessible if a fire should occur. Do not set up so that it is necessary to reach through the assembly to turn water, gas or electricity on or off.** * **Limit flammable liquids to amounts actually needed for immediate use. The vapor of nearly all organic solvents is flammable. Keep open flames, electric sparks and heating elements away from solvents. Prevent vapors from escaping by keeping lids closed** ## Fire Extinguishers Fire extinguishers are located in the hallway outside each first-year chemistry laboratory. These are Multi-purpose Dry Chemical extinguishers (Type ABC) and may be used on Class A, B and C fires: * **Class A fires:** ordinary combustible materials (paper, wood, most plastics) * **Class B fires:** flammable (combustible) liquids (gasoline, solvents, paint, oil) * **Class C fires:** electrical equipment (appliances, wiring, circuit breakers, outlets) To operate a fire extinguisher, use the PASS technique: * **Pull** the pin or locking device * **Aim** low, at the base of the fire * **Squeeze** the handle * **Sweep** slowly and evenly across the base of the fire. Only attempt to extinguish a fire if: * Everyone is leaving the room, and someone is dialing 911 to call the fire department. * The fire is small, not spreading, and the smoke or heat does not pose a threat. * Your extinguisher matches the type of fire you are attempting to fight. * You have confidence in fighting the fire and are familiar with the use of the extinguisher. Remember: Don't get trapped by fire. Always keep your back to a clear exit. # Safely Handling Chemicals Before using a chemical, you should become familiar with the boiling point, flash point, vapor pressure, toxicity, explosive limits, incompatibilities and other special precautions. This information is available to you in the laboratory in the MSDS binders. Nearly all chemicals are poisonous to the human body to some degree, and it is important to use proper caution at all times when handling chemicals. Vapours create most of the dangers in the laboratory. They may be toxic, flammable or both. Chemicals of these types should be handled in ventilated hoods in such a manner that the vapor will be carried away. When handling chemicals, keep hands (especially gloved ones) away from your face, eyes and skin until you have washed thoroughly. Never test chemicals by taste. To sample a gas by odour, fan some toward the nose with the hand after filling lungs with air. Use a rubber bulb to fill a pipette, do not pipette chemicals or start siphons by mouth. Pour acids into water while agitating, never pour water into acid. Stoppers should be held out of contact with anything but air while pouring from a bottle. If a spill occurs chemicals should be flushed off a bottle to protect the next user. Re-cap or stopper all chemical containers immediately. Chemicals are generally expensive. An estimation of the quantity required should be made at the beginning of each experiment. Any excess chemical must not be returned to reagent bottles but disposed of in the appropriate waste container. Chemicals that react to give off dangerous gases, cause fire or explosion should not be kept in proximity to each other. Unlabelled chemicals must not be used. All spills must be cleaned up immediately and the instructor notified. A gas or open flame must never be used to heat flammable liquids. An electric heating mantle or steam bath is most desirable. Neutralize acid or base (clothing, desktop or floor) by washing with plenty of water. Spill kits are available in the storeroom to clean up large amounts of either acid or base. For each experiment special disposal containers will be provided for waste chemicals, all chemicals must be disposed of in these containers. Nothing goes down the sink drains! # Safely Handling Glassware Laboratory glassware is generally fragile, and many unnecessary and painful accidents have occurred because of improper handling. Learn the names of the glassware, you will be using in the laboratory so that you can be sure to use the correct item for each procedure. Chipped or broken glassware should be discarded into specially marked "Glass Waste" containers for disposal. Broken glass should be collected with a brush and dustpan. Absorbent cotton may also be used to pick up fine pieces of broken glass. Cotton should be held with tongs. Never use a paper towel to clean up broken glass. Glassware that is chipped or cracked can break suddenly when heated or cooled, often creating a chemical spill or resulting in injury to the experimenter. Inspect beakers and flasks thoroughly for damage before each use. Vacuum flasks will collapse violently under vacuum if cracked, chipped or otherwise weakened. Tamping flasks when suction is on full is an unsafe practice. Erlenmeyer and other thin-walled flat bottom flasks, are not safe for use under vacuum. Release any vacuum from all parts of apparatus before disconnecting. Carry glass tubing and long glassware (burettes, pipettes, thermometers) vertically rather than horizontally. Apparatus that can roll such as tubing, glass thermometers, pipettes, etc., should be placed on the bench at right angles to the edge to keep them from rolling onto floor. All containers should be completely emptied and rinsed before cleaning. Organic residues can react with strong oxidizing agents. Pipettes with ragged-edges or shortened ends should be discarded. Appropriate measuring tools and extra care should be used when working with some of corrosive materials. # Electronic Equipment Safety * Do not immerse electronics in water. Use a damp cloth to surface clean if necessary. * Do not pour over electronic equipment or set up your workspace in a way that increases the chance of splashes or spills on electronics * Electrical cords should be kept out of contact with liquids at all times. # Locker Assignment ## Locker Check-In procedure - First day in the lab Students work with a partner for all experiments in CHEM 120L. The first day in the lab will include assignment of partners and a locker check-in. Once you have a partner, follow this procedure for the locker check-in: * Get a pink key requisition slip from the instructor. Read, complete, and sign the slip. * Take the key slip to the first-year storeroom (between the two labs) to get your locker key. This key opens both the top and bottom drawer of your locker. * Check the equipment against the list below. Anything missing or broken can be replaced at the storeroom. Today is your only chance to replace equipment for free. After today this equipment is your responsibility; no one else uses your equipment. You and your partner are the only people who have keys for your locker. At the end of the term, you will have to pay to replace any missing or broken equipment. * Remember to lock both drawers of your locker after each lab period. **Locker equipment list:** - 2 beakers, Griffin, 50 mL - 7 beakers, Griffin, 100 mL - 2 beakers, Griffin, 250 mL - 1 beaker, Griffin, 400 mL - 1 beaker, Griffin, 600 mL - 1 beaker, Griffin, 1000 mL - 1 bottle, Boston round, 500 mL - 1 bottle, polyethylene, 1 L - 1 wash bottle, poly, 500 mL - 3 flasks, Erlenmeyer, 125 mL - 3 flasks, Erlenmeyer, 250 mL - 1 test tube rack - 12 test tubes, 20 x 150 mm - 1 graduated cylinder, 10 mL - 1 graduated cylinder, 25 mL - 1 graduated cylinder, 100 mL - 1 glass funnel - 1 plastic burette funnel - 1 watch glass, 100 mm - 2 stirring rods, glass - 1 flint lighter - 1 test tube brush, small - 1 test tube brush, large - 1 test tube clamp - 1 crucible tongs - 1 scoopula - 1 dropper, glass - 1 dropper, plastic ## Locker Check-Out procedure - Last day in the lab The last day in the lab will include a locker check-out, this is the day students are expected to pay for missing or broken equipment. Follow these instructions for locker check-out: * Remove everything from your locker, clean the drawer and equipment if necessary. * Check the list above, make sure everything is present and in good working order. * Replace any missing or damaged equipment by purchasing it from the storeroom. * Ask your TA to check your equipment, do not return the equipment to your drawer. * Once the locker equipment is accounted for, and you have returned your locker key to your TA, you will receive a signed check-out slip indicating that your locker equipment is complete. Take this slip to the storeroom and exchange it for the pink key requisition slip you filled in on the day of check-in. # Experiment 1: Reactions of Copper ## Techniques to review before coming to the laboratory: * Appendix B: recording data and observations, significant figures * Appendix C: quantitative transfer, filtration * Waterloo LEARN videos: analytical balance, top-loading balance, Bunsen burner, washing glassware, fume hoods, snorkels, filtration ## Type of post-lab report: * Modified formal report (report sheets + formal conclusion) * Review Appendix A: Lab Reports - conclusion * Hand in at the beginning of your next scheduled lab ## Learning outcomes: By completing this experiment and report, you will: * Gain familiarity with the chemistry lab, equipment locations and chemical dispensing areas. * Practice working safely in a fume hood, and under snorkel exhaust vents. * Use the techniques of quantitative transfer, decanting and vacuum filtration. * Practice using Bunsen burners, analytical and top-loading balances. * Be required to properly record data recording and utilize a variety of analysis methods. * Assess the effectiveness of experimental processes and reactions. * Classify reactions by type using a simple classification structure. ## Introduction In nature, copper is found most commonly in the minerals chalcopyrite, chalcocite and bornite. As global for copper demand increases, some industries question if our natural resources can match the demand, emphasizing the importance of our ability to isolate copper from recycled materials. Knowledge of the reactions involved in the isolation and purification of copper, and an understanding of its reactivity is valuable. As with any reaction, the purification of copper or production of any copper compound presents its own problems based upon such things as availability of equipment, isolation from contaminants, percentage yields, and value or toxicity of by-products. This experiment produces a series of copper compounds from metallic copper, and demonstrates how metallic copper can be recovered from its compounds: * Cu → Cu(NO3)2 → Cu(OH)2 → CuO → CuSO4 . 5H2O → Cu The initial copper is to be eventually recovered as metallic copper, isolated as a pure substance, and weighed. To recover nearly all the copper as pure copper, try to prevent losses by avoiding spattering while boiling, leaving product on the sides of beakers, and spilling of product. Purify precipitates by washing efficiently and then drying appropriately before weighing. ## Classifying the types of reactions in this experiment: There are many differing methods for classifying reactions, often looking at different aspects of the reactions. For this experiment we will use a simple classification scheme based on three outcomes: combination, decomposition and displacement. ### Combination reactions Involve two or more elements or molecules coming together to produce a new molecule. For example: 2 Na + Cl2 → 2 NaCl ### Decomposition reactions Occur when a molecule is broken down to form smaller molecules or elements. This type of reaction is often initiated by heat or light. ### Displacement reactions Involve an exchange of components between molecules or atoms. These reactions are further categorized based on how many components are exchanged. * **A single displacement** involves the exchange of one component: * AB + C → AC + B * For example: 3 AgNO3 + Al → Al(NO3)3 + 3 Ag * **A double displacement** exchanges two components: * AB + CD → AD + BC * For example: NaCN + HBr → NaBr + HCN * **A special case of double displacement, called a neutralization, occurs when an acid and a base react to form a salt and water:** * AH + BOH → AB + H2O * For example: HCl + NaOH → NaCl + H2O ## Methods of analyzing reactions - % yield and % atom economy The percent yield (or % recovery) is a measure of how much of the desired product is obtained from a reaction. It is calculated in this case using the recovered mass of solid copper and the starting mass of the initial copper, using the following equation: % yield = actual yield (g) / theoretical yield (g) x 100% The % yield method of assessing the effectiveness of a reaction looks only at how much of the desired product is obtained from the reaction and ignores any unwanted side products. It assumes that the product recovered is pure, which may not be true in every case. With the development of new green chemistry policies, chemists are now interested not only in maximizing yield, but also on minimizing unwanted (and sometimes dangerous) by-products. One method of assessing whether a reaction meets green chemistry standards is to determine the percent atom economy of the reaction. This method compares the mass (using stoichiometric molar masses) of the desired product, to the combined mass of all reactants, using the following equation: % atom economy = molar mass of desired product / molar masses of all reactants x 100% ## Procedure ### Use the blue requisition slips on top of the bench turrets to sign out the following items from the Storeroom: * 1 evaporating dish * 1 Buchner funnel * 1 500 ml vacuum flask * 1 length of vacuum tubing ### Pick up from the side bench, equipment drawers or cabinets: * 1 Bunsen burner * 1 metal rod * 1 ring clamp * 1 wire gauze * 1 55 mm #1 filter paper ### De-ionized (DI) water: DI water is used for all experiments in the first-year chemistry lab. Tap water (from the bench sinks) is only used for washing your hands and washing dishes. When you arrive in the lab each day, fill your wash bottle with DI water from the labelled taps at the side bench sinks. (Ask your TA if you can't find it!) This will save time as you will always have DI water when you need it. Empty your wash bottle at the end of each lab, do not store DI water in your locker. **A note on significant digits (significant figures) in procedures**: Values in the procedures are always written with the appropriate number of significant digits, thus, the digits in the value indicate the accuracy required in your measurement. If you are asked to measure 5.00 mL of a liquid, you must choose a measuring tool that will measure with an accuracy of ± 0.01 mL, a pipette or burette would be required. However, if you are asked to measure a volume of 5 mL, (this would mean 5 ± 1 mL) a graduated cylinder would be adequate. **Record all values with the appropriate significant digits on your data sheet.** ## Reaction 1: Copper metal to copper (II) nitrate (Time required: 10-15 minutes) ### Obtain a length of copper wire (99.99% pure) and a piece of sandpaper from the side bench. Sand the wire to remove any coating that may have been added by the manufacturer to prevent corrosion/oxidation. After sanding, take the wire to the analytical balance room to weigh. From the list on the balance room wall find the number of the analytical balance you are to use. You share this, with the students working beside you. Only the students performing the weighing are allowed inside the balance room (one partner only, no spectators please). All digits displayed on the analytical balances should be recorded (this will give you a mass in grams with 4 decimals, that is, these masses are accurate to 1/10000th of a gram). Record the mass of your copper wire on your data sheet. ### Back at your workbench, place the copper wire in a labelled 250 mL beaker (you need to be able to identify which beaker is yours) so that the wire sits flat on the bottom of the beaker. This is done so that the entire piece of wire is immersed in the small volume of acid you will add at the next step. (Coiling the wire works well here.) ### Take the beaker containing your wire and a 10 mL graduated cylinder to the fume hood. In the fume hood, add 10 mL of concentrated (15.8 M) nitric acid, HNO3. Once you have added acid to your beaker, place it towards the back of the fume hood and move away from the fume hood to let others begin their reaction as well. (You can observe this reaction from a distance.) ### Let the nitric acid and the copper wire react in the fume hood while you observe and record a description of this step of the reaction on your data sheet. Do not remove the beaker from the fume hood yet! ### After the wire has dissolved, swirl the beaker in the fume hood to remove any gases trapped in the solution. This may take a while! You may safely remove your beaker from the fume hood when no gas is observed upon swirling and the solution is bright blue. Observe and record a description of this step of the reaction on your data sheet. This chemical change may be represented by the equation: Cu (s) + 4 HNO3 (aq) → Cu(NO3)2 (aq) + 2 NO (g) + 2 H2O (l) ## Reaction 2: Copper (II) nitrate to copper (II) hydroxide (Time required: 5 minutes) 1. Back at your workbench, dilute the resulting solution by quickly adding 25 mL of deionized (DI) water to your ample. (This is a fast addition, it is important that you do not add this water slowly, do you know why?) 2. Locate the 6.0 M NaOH on the side dispensing bench. Measure 25 mL into a small beaker or graduated cylinder and bring it back to your workbench. This solution will be added to your copper solution slowly, in small increments. 3. Slowly add the NaOH to the diluted Cu(NO3)2 solution. After the addition is complete, stir the solution and check the pH using the pH paper available on the side bench. To check pH: remove your stir rod from the solution and touch the rod to a small piece of pH paper. The solution should be strongly alkaline (pH > 10) after this addition. If the pH is too low at this step, add an additional 5 mL of NaOH and check the pH again. Repeat this 5 mL addition if necessary. Observe and record a description of this reaction on your data sheet. ## Reaction 3: Copper (II) hydroxide to copper (II) oxide (Time req'd: 20-70 minutes) ### Separation and purification of a gelatinous precipitate such as Cu(OH)2 is difficult because its separation by filtration proceeds slowly. After separation, the process of washing it on filter paper to remove soluble salts is time-consuming and not very effective. Since Cu(OH)2 decomposes upon heating to form a non-gelatinous precipitate, CuO, the copper will be recovered at this stage as CuO rather than Cu(OH)2. 1. **Heating step: 10-15 minutes** (a) Set up a heating apparatus as shown. You control this setup, position your clamp such that you will be able to use a small, easily controlled flame. (b) Heat the mixture gently, stirring continuously to prevent bumping, until the boiling point is reached. Continue to heat gently for one minute to better coagulate the CuO and to ensure that all the blue Cu(OH)2 has been converted to black CuO. At this point the solid black CuO should separate from the clear liquid supernatant. 2. **Observe and record a description of this reaction on your data sheet.** 3. **Filtration step: 10-60 minutes** (a) Once you have produced solid CuO, you will isolate it from the aqueous solution using vacuum filtration. Set up a vacuum flask with a Buchner funnel as shown, and filter as described in Appendix C. (b) To quantitatively transfer all of the CuO from the beaker to the Buchner funnel, swirl the beaker gently before adding solution to the funnel. (c) When no more of the thick solution can be poured or scraped into the funnel, use three small portions of deionized water (~10 mL) to rinse the remaining CuO out of the beaker into the Buchner funnel.