Introductory Laboratory Manual Student ………………………………… Developed for CFFET D. Hatton 2012 1 Contents Units ........................................................................................................................... 4 Introduction ................................................................................................................ 5 Workplace protocols ................................................................................................... 8 Safety in the Laboratory ............................................................................................. 9 Laboratory hazards .................................................................................................. 10 Laboratory rules and regulations .............................................................................. 13 Practical 1.1 Laboratory Layout ................................................................................ 14 Clean-up of spills .................................................................................................. 15 Practical 1.5 Safety in the laboratory ........................................................................ 16 Laboratory Safety Information .................................................................................. 19 Dangerous goods 'Class' labels ............................................................................... 20 Practical 1.2 Laboratory signs and labels ............................................................ 22 Practical 1.3 Laboratory hazards ......................................................................... 25 Introduction to Basic Chemical Laboratory Equipment ............................................. 27 Observation skills ..................................................................................................... 28 Equipment for handling chemicals............................................................................ 29 Practical Equipment identification (Part 1)................................................................ 30 Basic Material Handling Techniques ........................................................................ 35 Practical work 5.1 Basic material handling techniques .......................................... 36 Practical Liquid handling ......................................................................................... 37 Practical work 5.3A Introductory Volume Handling Measurements ......................... 38 Measurement Of Mass .......................................................................................... 39 Practical work 5.2A Introductory weighing task ..................................................... 40 Other basic laboratory Procedures ........................................................................... 41 Practical work 5.5A Simple filtration ...................................................................... 42 Heating in the laboratory .......................................................................................... 44 Practical: 4.4 Practical: Heating devices ............................................................................ 45 Application of heating equipment ........................................................ 48 Practical 5.4A Introductory Solution Preparation ...................................................... 54 Safety Audits and Checklists................................................................................. 56 Laboratory Safety Checklist ..................................................................................... 58 Open ended project .................................................................................................. 61 2 Basic Arithmetic........................................................................................................ 62 3 Units These units are designed to provide fundamental chemical knowledge and skills to allow the participant to work safely in a chemical Laboratory. The satisfactory completion of this resource can be used as evidence against the following Units: MSL913001A Communicate with other people MSL922001A Record and present data MSL943002A Participate in laboratory/field workplace safety MSL933001A Maintain the laboratory/field workplace fit for purpose MSL973001A Perform basic tests MSL973002A Prepare working solutions MSS024001A Work and communicate effectively as an environmental Technician Note: The particular unit depends on the course of enrolment Content includes: Classification and properties of matter, including chemical and physical changes Systematic naming of chemicals Disposal of chemicals Investigations of simple chemical reactions Working safely with chemicals and equipment Following instructions both written and verbal Assessment is on going and may include: log book written assignments practical work observation practical work assessment completion of workplace documentation 4 Introduction The Chemical, Forensics, Food & Environmental Technology (CFET) section of the Hunter Institute has developed this manual to help students evidence the knowledge, skills and attitudes they are developing for scientific laboratory work. This manual is designed to be used in conjunction with the text ―Practical Laboratory Skills‖ (1995 Harcourt Aust) by Krajniak, Barker & Fullick. Laboratory Practice is a general term used by this teaching section to describe standard operating procedures in a typical science laboratory. Activities in this manual have been designed to help candidates learn and practice skills necessary to be deemed competent in some of the competency standards described in the Laboratory Operations Training Package – MSL09. Laboratory Practice covers all the specified activities, defined in TAFENSW curriculum, to develop general science laboratory competencies. Log Book This manual will serve as a record of activities used for skills development and summarises the actual performance of the individual named on the front cover. This manual only provides brief introductory notes for each activity and it is expected that the teacher and the textbook will provide more extensive details of basic theory and the contexts in which the theory may be applied. This manual provides suitable result sheets to record and report the laboratory activities, observations and measurements made which summarise the learner‘s work. These completed result sheets will become part of the evidence of the learner‘s skills needed to assess competency. An alternative logbook will be required for completion of the investigative tasks undertaken in the Applied Laboratory section. Introductory Laboratory Practice - details and back-ground information Class Times: …………………………………………………. Class Locations: ………………………………………………… Staff details: Head Teacher ………………………………………… Class Teacher ………………………………………… Technical staff……………………………………………… 5 Vocational Science Training This course is part of the vocational science training provided by this institute. This training is needed in a range of workplaces and by different employers. Relevant workplaces and employers include: High school science departments preparing practical classes for teachers manufacturing – making plastics, pharmaceuticals, chemicals, building materials, process plants etc food technology – making processed food such as drinks, cereals, smallgoods, canned goods, dairy, margarine etc public authorities such as DECC, CSIRO, education, councils Typically, these workplaces and employers may have needs such as: research, quality assurance, product development and troubleshooting, environmental monitoring, training, etc. These workplaces and employers use science technicians to perform testing, measurement, technical supervision, calibration, customer liaison, compliance monitoring with respect to legal and commercial quality standards, etc. This course assumes no previous knowledge or skills and will bring you up to workplace standards for: safety systems – hazard control and risk management information systems – signs, SDS, handbooks, etc equipment – identification, applications and correct usage procedures – how to correctly perform common basic procedures and techniques physical testing – pH, melting point, refractive index, conductivity chemical testing – gravimetry, titrimetry, etc data processing – turning measurements into meaningful numbers and comparing your answers to industry standards By the end of the units you will have a good idea of what professional science training is available from TAFENSW and what sort of jobs it can lead to. What is in it for you? Better idea of science as a job Credit in C3, C4 and diploma courses in laboratory technology Taste of competency based training – assessed on what you can do competently rather than what you know / can memorise. Competency with essential workplace protocols 6 How to I work with this manual? You will be guided through the work by your teacher. There will be lots of resources available for you. These will include: Course notes Laboratory staff Safety Data Sheets Methods of analysis Revision exercises who is your indication that there is an activity to complete. 7 Workplace protocols 1. Safety Procedures (a) (b) (c) (d) (e) (f) (g) Consult Safety Data sheets* and method of analysis for advice on hazards and precautions to be taken Wear appropriate PPE Use fume hood etc as necessary Maintain tidy workspace Exercise care not to endanger other people Observe emergency procedures Report spillages and all accidents 2. Recording and Reporting (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l) (m) (n) (o) Register samples into laboratory system Label samples Record which tests the sample should undergo Record sample description, compare with specification, record and report discrepancies Record calibration results for instruments/equipment in tables and/or charts, following quality system Keep records of calibration status and calibration schedule for instruments / equipment Report faulty equipment Keep records of solutions prepared, by expected use-by date, and by name of person who prepared them Record results legibly, and chart when required to identify trends Interpret trends Identify and report atypical results promptly to appropriate personnel Record approved results into workplace system Comply with quality system Report all accidents and potential hazards Maintain confidentiality of workplace information 3. Sample Handling (a) (b) Maintain sample integrity Prepare sample and standards for test 4. Testing (a) Refer to workplace procedures manual for standard method Conduct tests according to workplace procedures Clean up spills promptly Record results according to workplace procedures, without alteration Calculate results, checking against expected values and correcting errors Trouble shoot basic problems with procedure or equipment which have led to atypical results (b) (c) (d) (e) (f) 5. Equipment and Reagents (a) (b) (g) Set up equipment and reagents Check calibration status of equipment; calibrate if necessary Monitor shelf-life of working solutions Prepare solutions when necessary, label and log into laboratory register Clean and care for test equipment and work space Dispose of faulty equipment or quarantine it for repair Store unused reagents 6. Wastes (a) (b) Minimise generation of wastes Collect, sort and dispose of wastes in accordance with procedures (c) (d) (e) (f) * SDS‘s were up until January 1 2012 referred to as MSDS (Material Safety Data Sheets) 8 Safety in the Laboratory Purpose: This section is designed to provide a brief overview of work safety in the laboratory. You will need to refer to the text for laboratory safety for additional information. Occupational health and safety laws have greatly improved safety and well being in the workplace. All employers must provide safe and healthy work conditions, all workers must work within the safety systems and both groups must accept responsibility for identifying and controlling hazards and minimising risk of harm. These laws are continually being reviewed and the current Work Health and Safetyy Act 2011 resulted in a change from 1 January 2012. Any laboratory has a range of hazards that need to be controlled to minimise the risk of harm. A working laboratory is really not much different to working in your home kitchen! What is a hazard? What is risk? What does hazard control mean? What controls are available for different hazards? 9 Laboratory hazards Physical Chemical Biological Electrical Explosives Infective agents – bacteria, viruses, etc Mechanical Corrosives Animal and plant toxins Manual handling Flammable gases Allergens Cuts Flammable liquids Sensitisers Burns Flammable solids Biological active substances Radiation Radioactivity Compressed gases Oxidisers Mixes of the above Dust Mixes with other types of hazards Confined space Poisons Stress Note that there are acute vs chronic issues, dose and response issues, exposure standards, monitoring / awareness problems Noise Light Of the above laboratory hazards are there any that also apply to your kitchen? Use an asterisk * to indicate those that also apply to your home. 10 Chemicals can be hazardous because of a range of properties. They may be: toxic/poisonous irritating flammable explosive corrosive mutagenic, carcinogenic, teratogenic Effects may be acute or chronic. A chemical is only dangerous if it enters your body. This can only occur by: inhalation absorption ingestion injection 11 What controls exist for each of these chemical hazards? The law (Work Health & Safety 2011) now requires information sources about hazardous chemicals to be supplied. They are called Safety Data sheets (SDS) and they help you to find out about dangerous properties of chemicals and what measures to take to reduce harmful effects. Typically a SDS provides information about: common names and identification codes for the material physical properties major hazards of the material acute and chronic symptoms of exposure exposure standards medical advice spill and other emergency responses others Use the SDS provided and identify information relating to the hazardous nature of the material. 12 Laboratory rules and regulations 1. Always wash your hands before you leave the laboratory 2. Only supervised work is permitted in the laboratory 3. Chemicals and equipment are not to be taken from the laboratory 4. Safety glasses, laboratory coats and appropriate shoes must be worn in the laboratory at all times 5. Clean-up spills immediately 6. Act responsibly - the laboratory is not a playground, racetrack or amusement parlour 7. Long hair must be tied back 8. You must be aware of the location and operation of safety equipment 9. All accidents and incidents must be reported 10. Consult the SDS for unfamiliar chemicals 11. Spillage of any chemical on the skin or eyes should be immediately treated with copious quantities of water and the supervisor‘s attention sought 12. Eating and drinking in the laboratory is banned 13. Fume cupboards should be used for work involving dangerous gases or vapours The Laboratory is a safe place to work if you follow the rules 13 Practical 1.1 Laboratory Layout Date completed: Purpose _____________________ Teacher Check _______________ Analyst signature ____________ To become familiar with the layout of the work area, in particular, those areas and pieces of equipment that deal with safety. Procedure: Draw a map of the laboratory, which shows the location of the following features: Fire extinguishers, fire exits, fire control equipment; special storage cupboards, safety showers, eye wash stations, first-aid, fume cupboards, antidotes, laboratory store, ovens, balances, waste disposal facilities. 14 Clean-up of spills Common spills which can occur in the laboratory include solid reagents, solutions of all kinds, various organic solvents and special ‗nasties‘ such as mercury. All spills are to be treated according to the immediate dangers. For example it may be necessary to: evacuate (e.g. poisonous gas or vapours) ventilate (e.g. organic solvent fumes) isolate services (e.g. flooding around electrical services) contain (e.g. prevent spread of fluid or other material beyond the site of the spill) absorb (e.g. use an inert absorbent to soak up a spill) neutralise (e.g. concentrated acids and bases need to be neutralised first to minimise corrosion to the cleaning equipment and the cleaner) clean up (e.g. sweep up the solid residues) dispose (e.g. may need a clean-up service because of the hazardous wastes) rehabilitate (e.g. surfaces may have been damaged and will require refinishing). The Golden rules for personnel safety in the laboratory: Leave the laboratory clean and tidy Put your equipment away Clean up all your mess Keep your equipment and community property clean and well maintained If you borrow anything, return it Any safety and hazardous situations or issues should be drawn to the supervisor‘s attention. 15 Practical 1.5 Safety in the laboratory Date Completed: _____________________ Teacher Check ______________ Procedure: Analyst signature ____________ Observe the demonstrations on safety in the laboratory Give a brief description of the demonstration List the observations you made during the class and in the next laboratory session Comment on aspects of the demonstration that you found interesting, disturbing, informative etc Results: Test/ Demonstration Observation Comments Hydrochloric acid HCl + Meat Sulfuric acid H2SO4 + Meat 16 Test/ Demonstration Observation Comments Nitric Acid HNO3 + Meat Sodium Hydroxide NaOH + Meat Ammonium hydroxide NH4OH + Meat 17 Test/ Demonstration Observation Comments Propanone Acetone CH3COCH3 + Meat 18 Laboratory Safety Information Work health and safety laws have greatly improved safety and wellbeing in the workplace, by specifying the responsibilities and rights of both employers and employees. All employers must provide safe and healthy work conditions, all workers must work within the safety systems and both groups must accept responsibility for minimising risk. Laboratory workers who use chemicals and scientific equipment face additional risk from duties which involve manual handling, physical hazards, biohazards and hazardous substances. Chemical hazards are potentially so harmful that other laws also exist to deal with them, including environmental pollution laws, codes for transport of dangerous goods and workplace hazardous substances control regulations. Hazard Control All chemicals should be considered to be dangerous because they may be: toxic / poisonous : damage body organs or tissue by interfering with the normal chemical processes occurring in those tissues irritating: cause a bad response to eyes, skin and other organs flammable : burn or cause heat damage to tissue explosive: create a shock wave of high speed and high pressure that causes mechanical damage corrosive : chemically degrades tissue at the point of contact. Specific organs such as lungs, liver, eyes and skin may be affected or gross damage can occur at all points of contact. Damage can range from: slight tissue damage or irritation to total destruction minor, temporary change to widespread permanent damage immediate evidence of symptoms to long-term delay before onset. 19 Dangerous goods 'Class' labels Class 1 - Explosives Class 2 - Gases Class 3 - Flammable liquids Class 4 - Flammable solids Class 5 - Oxidisers 20 Class 6 - Toxic and infectious substances Class 7 - Radioactive material Class 8 - Corrosives substances Class 9 - Miscellaneous dangerous goods 21 Practical 1.2 Date Completed: Laboratory signs and labels ___________________ Teacher check _____________ Procedure Analyst signature ____________ Observe the laboratory signs and labels in the laboratory and throughout the building. Fill in the table below with at least six examples to show your understanding of each column heading: Sign identifier eg exit, fire, no smoking, etc Message being conveyed Significant aspects of the colour scheme Location 22 Sign identifier eg exit, fire, no smoking, etc Message being conveyed Significant aspects of the colour scheme Location Questions: Answer the following general questions about the signs and labels found in the laboratory and surrounding areas 1. Why are signs important in the laboratory? 23 2. List: other signs and labels which you believe could be necessary places in the laboratory where these missing signs should be located 3. Why do you think that smoking is not allowed within 10 metres of the building? 24 Practical 1.3 Date Completed: Procedure: Laboratory hazards __________________ Teacher check ___________________ Analyst signature ____________ Identify the hazards that you have found in the laboratory and indicate how you can work safely with these hazards. Use the table of physical, chemical and biological hazards given earlier for some ideas. Results: Hazard Possible effects of hazard Control measures 25 Hazard Possible effects of hazard Control measures 26 Introduction to Basic Chemical Laboratory Equipment Basic Laboratory Equipment Laboratory testing is used to answer at least one of these basic questions: ―what is this material?‖ ―what are the components in this material?‖ ―how much of each component is in this material?‖ In other words, the lab can analyse a sample to describe what it is or what is in it –is there: mercury in this fish? salmonella in this chicken meat? cocaine in this powder? alcohol present on this person's breath? The lab can analyse a sample to describe how much of any component is in it: how much mercury in this fish? how much salmonella in this chicken meat? how much cocaine in this powder? how much alcohol present on this person's breath? The ‗what‖ questions are questions about quality and such laboratory work is called qualitative analysis. (if you answer 'yes' to the 'what' questions above, what does it tell you about quality of each sample?). Qualitative analysis requires qualitative equipment and the major focus is on isolating and purifying components and identifying components. Accuracy in measuring mass and volume is not a big deal because we are not answering anything about ‗how much‘. It is quite acceptable to use measuring cylinders and 2- and 3- decimal place balances. Accuracy in measuring physical properties, eg RI, pH, m. pt., etc is very important because we use these numbers to decide on purity and identity. The ‗how much‖ question is a quantity question and such laboratory work is called quantitative analysis. 27 Observation skills are particularly important in aspects of laboratory work. We use all senses to assist in working safely and also in noting aspects of our practical work Take a candle and: 1. Make as many observations as you can about your candle. 2. Light your candle and record all your observations 3. Blow out your candle and record your observations 4. Identify your observations as qualitative or quantitative 28 Equipment for handling chemicals Choosing the right equipment to handle the different types of chemicals in the laboratory will depend on your purpose, eg: storage (S) transfer (T) processing (P) measurement (M) Storage containers for liquids and solutions can be large or small vessels. Aspirators and carboys (eg 10 – 20L), drums ( eg 200L), and Winchester bottles (2.5L) will hold large amounts. Smaller amounts can be stored in bottles whose volume will be 1 L or less. Flasks, beakers and conical beakers are useful for transferring liquids. They are available in various sizes. Spatulas, funnels, basins, watch-glasses, dishes and sample tubes have specific purposes within the laboratory. Measuring cylinders, pipettes, graduated pipettes, burettes and volumetric flasks are designed to measure volume, with varying degrees of accuracy and reliability. The most common material for these is glass although plastic is also common. Other construction materials include stainless steel and platinum. Quantitative analysis uses quantitative equipment and the major focus is on numerical accuracy. Volume and mass must be measured as accurately as possible to get the best possible measure of ‗how much‘. Measuring cylinders and 2- and 3decimal place balances are no longer good enough and we must use pipettes and burettes and volumetric flasks and 4-dp balances. In order to do qualitative and quantitative analysis reliably, the lab needs to have a wide selection of specialist equipment and procedures in place to do the measurements. The equipment available for handling the materials necessary in the laboratory includes glassware, balances and a host of storage, transfer, measuring and processing tools. 29 Practical Equipment identification (Part 1) Analyst signature ____________ The following table lists basic apparatus used in the laboratory. Complete the table by giving a use for the equipment and any safety features that need to be considered. Diagram Name Use / Safety/ Range of sizes 30 Diagram Name Use / Safety/ Range of sizes ` 31 Diagram Name Use / Safety/ Range of sizes 32 Diagram Name Use / Safety/ Range of sizes 33 Diagram Name Use / Safety/ Range of sizes 34 Basic Material Handling Techniques In any laboratory, certain techniques are regularly performed and are essential to most routine work. These techniques include the measurement and use of chemicals and other hazardous substances and the operation of laboratory equipment. A competent technician uses these basic techniques, confidently and without risk, in routine work and with any new procedures. Procedures include: material transfer weighing volume measurement solution preparation filtration heating, cooling and drying temperature measurement using gas cylinders particle size reduction cleaning and drying glassware. Material transfer Materials are routinely moved from one container to another during laboratory work. The transfer usually has to meet at least one of the following requirements: safety with materials which are toxic, corrosive or dangerous in some way. quantitative transfer where any loss will affect the accuracy of the task. contamination control either from the surroundings to the material or vice versa 35 Practical work 5.1 Basic material handling techniques Date Completed: ______________________ Teacher check ________________ Purpose: Analyst signature ____________ All chemicals whether solid, liquid or gas must be handled with caution. This practical looks at the techniques to be employed when transferring solids and liquids. Procedure: Observe the demonstrations of material transfer shown by your trainer. Identify the mistakes and indicate how the process should be completed. Procedure Errors Corrections 36 Practical Liquid handling Date Completed: ______________________ Teacher check ________________ Analyst signature ____________ Use the equipment provided to practice pouring and transferring liquids from one container to another. Complete the following table . Equipment Major Application Convenience of Use Winchester bottle Laboratory storage bottle Aspirator Measuring cylinder Beaker Conical flask Evaporating basin Sample tubes Desiccator 37 Practical work 5.3A Introductory Volume Handling Measurements Date Completed: ______________________ Teacher check ________________ Procedure: Analyst signature ____________ For all workstations complete the table following the instructions provided Results: Workstation 1 Identify the container, its accuracy and the volume contained. Vessel name Workstation 2 Volume How accurate is your measurement? Identify the equipment needed to transfer the volumes Vessel name Specified volume Teacher’s Signature 38 Measurement Of Mass Mass in the everyday world is measured on scales such as those used for people or vegetables or fertiliser. Bigger versions are used to check trucks or bales of wool and smaller versions are used by the jewellery trade. In the scientific world, the term ‗scales‘ is replaced by the term ‗balance‘ when describing tools for the measurement of mass. Figure 4.6 A two-pan beam balance Laboratory Weighing Weighing of materials is fundamental to most procedures. You should be competent at working with each of the balances found in the general laboratory. Weighing rules all balances must be clean, level and zeroed all chemicals must be weighed by difference in a container don‘t weigh hot or wet objects clean up all spills immediately check the balance has returned to zero and reset it before you leave. Common terms used with weighing or the use of a balance include: clean: nothing on the balance pan level: the workbench and the balance need to be horizontal balance reading: the mass on display true mass: the mass of the sample after the container mass has been subtracted reset: leave the balance clean, level and zeroed weighing by difference: an empty container is weighed, the sample is added to it and the mass of the container and material recorded, the difference between the final mass and the empty container is the mass of the material taring: the balance pan is adjusted to read zero with the empty container sitting on the balance pan, when the material to be weighed is added, the displayed weight is the weight of the added material only 39 Practical work 5.2A Introductory weighing task Date Completed: ______________________ Teacher check ________________ Purpose Analyst signature ____________ The aim of the practical is to become familiar with the different types of balances available in a general laboratory. Your instructor will demonstrate the correct procedures to follow when using a balance. Procedure: Use the range of laboratory balances supplied as shown during your teacher‘s demonstrations. You will perform repeated measurements which will be used to check your accuracy and that of the balances. Record the capacity and sensitivity of the balances. Results: Balance Object Code ........ Object Code........ Object Code ........ Triple Beam: Capacity: ........... Sensitivity;.......... 3 dp top pan Capacity: ........... Sensitivity .......... 4 dp analytical Capacity ............ Sensitivity ......... 40 Other basic laboratory Procedures Separation of one component from another in a mixture can be a routinely necessary task in a laboratory. Filtration is used to separate an insoluble solid from a liquid. The procedure requires the use of a barrier called the filter, which is permeable to the liquid but retains the solid. The liquid portion is termed the filtrate or mother liquor and the solid is the filter cake or residue. Two common approaches to filtration are: gravity vacuum assisted Gravity filtration is a simple method of separating a solid from a liquid. It involves the use of a filter paper, available in various pore size and diameter, folded and placed in a filter funnel. The mixture is poured in the top, the paper allows the liquid to pass and the residue is left behind. Vacuum filtration is used where large quantities of solids and/or fluids are involved and fast separation is required. Problems arise if the solid is very fine or gelatinous. 41 Practical work 5.5A Simple filtration Date Completed: ______________________ Teacher check ________________ Purpose: To become familiar with simple filtration techniques, following instructions and noting safety requirements. Analyst signature ____________ Note: The chemicals in this practical are very toxic. Ensure that any spills are reported and also ensure that hands are properly washed if skin contact occurs and before leaving the laboratory. 1. Record the identity and quantity of each of the chemicals 2. Dispense an aliquot for each reagent bottle into a clean dry beaker 3. Carefully mix, using a glass stirring rod, the beaker contents over a steam bath for five minutes 4. Cool the beaker in an ice bath 5. Set up a filtration apparatus as shown by your teacher and using a labelled, preweighed filter paper filter your sample. 6. Wash the filter cake well with distilled water 7. Transfer the filter cake and filter paper to a labelled watch-glass and allow to dry 8. Reweigh and determine the amount of solid material. Results: Identity of solution 1 Volume of solution 1 used Identify of solution 2 Volume of solution 2 used Mass of empty filter paper Mass of filter paper + precipitate Mass of precipitate 42 Questions: 1. When is filtration a suitable method of separation? 2. One of the solutions you worked with contained lead. Why is it necessary to be extremely careful when working with this chemical? How would you find out the necessary safety requirements for working with lead solutions? 3. Why was it necessary to stir the solution over a water bath? 4. Why was it necessary to allow the solution to cool before filtration? 5. When filtering the solution is not filled to the top of the filter paper, why? 6. Draw a diagram to represent the simple filtration apparatus. 7. List all the possible places where losses may have occurred. 43 Heating in the laboratory A laboratory also will have an array of heating, cooling and drying equipment such as gas burners, heating mantles, muffle furnaces, hot plates, steam baths, ovens, desiccators and refrigerators. Common gas burners include the bunsen, the meker, batswing and microburner. These burners all depend on a supply of fuel gas and air. The efficiency and heat output of any burner can be controlled by selecting the amount of air and/or gas which passes through the burner. Your teacher will demonstrate the correct ignition procedure for the common laboratory burners . Generally if you are going to leave a bunsen burner alight, but not in use, the yellow ―safety‖ flame should be burning. Non-flame devices are versatile and much safer for use with flammable materials. These include electric hotplates, drying ovens, muffle furnaces, heating mantles and drying cabinets. 44 Practical: 4.4 Heating devices Date Completed: ______________________ Teacher check ________________ Procedure: Analyst signature ____________ Examine the heating equipment on display and complete the following table. Device Description Major Use Safety Hazards Flame dependent devices (Burners) Bunsen Meker Batswing 45 Device Description Major Use Safety Hazards Microburner non – flame devices Heating mantle Electric hot plate Muffle furnace Laboratory drying oven Heat lamp Steam / water / sand baths 46 Device Description Major Use Safety Hazards Others 47 Practical: Application of heating equipment Date Completed: ______________________ Teacher check ________________ Procedure: Follow the instructions for each task and record the data where required. Analyst signature ____________ Task 1 1. Unscrew the stack on each of the supplied burners and examine the features of each burner. Note the gas jet or nipple and the rotatable sleeve which admits air and mixes it with the gas as they moves up the stack. 2. Attempt to light the gas at the nipple. Note - the gas supply may need to be very low for this. 3. Replace the stack and light the Bunsen as demonstrated by your teacher. 4. Note the effect of sleeve positioning on the appearance of the flame. 5. Using the blue flame, turn the gas pressure down slowly so that the flame gets smaller and strikes back down the stack to burn at the gas nipple. This condition is extremely dangerous because: the Bunsen appears to be off and hence is a fire hazard the stack will be heated by the flame and will burn anyone who touches it 6. Repeat the above five steps with the Meker and micro-burners. Draw and label a Bunsen and discuss your observations below 48 49 Task 2 Use the supplied thermocouple to measure the temperature of various zones in both the ‗blue‘ and ‗yellow‘ versions of the Bunsen flame. Complete the following table: Zone of the flame being measured Yellow Flame temperature Blue Flame temperature (OC) (OC) Diagram to locate each zone Approx. 20cm above the tip of the flame At the tip of the flame 20 cm In the heart of the flame (top of blue cone) Level with the stack opening Task 3 This section is designed to investigate the changes which occur to the gas mixture in the flame. Following the demonstrations given by your teacher, examine the presence of zones of unburnt gases in a Bunsen burner as follows: 1. Use a thin glass tube inserted directly into the bottom of the blue cone to tap off some of its contents – attempt to ignite the gases at the other end of the tube 2. Pierce a live match with a pin inserted at right angles approximately half way along the match – suspend this match with its head pointing up, on the stack of an unlit Bunsen. Light the Bunsen, with the air hole open. 50 Observations Record your observations and provide an explanation of what is happening. Task 4 This section tests the efficiency of heating water in various containers with different heating equipment. You are to report on: the time taken for the water to boil the amount of heating control you have the safety of the method. Each of the containers should be about one third filled and heated as shown by your teacher. Container Heating device Time to boil (sec) Controllability or efficiency Safety hazards micro test tube Bunsen 51 Container Heating device Time to boil (sec) Controllability or efficiency Safety hazards micro test tube micro burner test tube Bunsen test tube micro burner boiling tube Bunsen boiling tube micro burner Beaker Bunsen (100 - 150mL) Beaker micro burner (100 - 150mL) Beaker steam bath (100 - 150mL) Beaker (100 - electric hotplate 150mL) 52 Questions: What is the major safety hazard when boiling liquids in test tubes? Which of the following would be suitable to heat water to boiling? heating mantle muffle furnace laboratory drying oven hair drier 53 Practical 5.4A Introductory Solution Preparation Date Completed: ______________________ Teacher check ________________ Procedure: Analyst signature ____________ You are required to prepare and validate known concentration solutions. Using an analytical balance weigh out accurately the mass of each solute indicated in the result sheet table. Quantitatively transfer the solid to a 100mL volumetric flask and make up to the mark with distilled water The teacher will show you the checks to be made on your sample and the previously prepared sample Results: Potassium Hydrogen Phthalate (Labelled as KHP) mass = 1.0 ±0.1g Your Solution readings Standard Sample readings Sample mass: Sample volume: pH reading Conductivity Potassium chloride (labelled as KCl) mass = 5.0 ± 0.5g Your Solution readings Standard Sample readings Sample mass: Sample volume: pH reading Conductivity 54 Questions: 1. Why is it important that an analytical balance is used to measure the mass? 2. Why is it important that the transfer of solid material is quantitative? 3. Why was a volumetric flasks specified in each case? 55 Safety Audits and Checklists One of the tasks of members of occupational health and safety committees is to carry out workplace inspections. These so called safety audits are carried out in order to: spot hazardous procedures or situations in the workplace assess the risk they pose to worker health and rank them in a priority order of seriousness so that resources can be directed to the most serious problems first recommend changes which will lower or remove the risk. This can be a daunting task, particularly in a large workplace. You can help your safety committee by carrying out safety audits in your own work area. A careful inspection using a standard safety checklist will help in this regard, by ensuring that all potential hazards are identified as quickly as possible and the risk they pose assessed. Many of the hazards which you find after going through a safety audit may be fixed by simple procedural changes, but others may require financial input (which requires management involvement), or technical advice. Members of your safety committee or your safety representative should be able to direct you to the correct source of any technical advice required. If not, consult your local occupational health and safety authority. How do I recognise a safety hazard? In many cases this is easy. Look for: untidy work areas, the use of damaged or inappropriate tools, poor lifting or manual handling techniques, failure to follow established safe procedures incorrect use of, or failure to use protective equipment. The identification of hazardous substances in the workplace is often a more difficult task, requiring more training and expertise. In this case you will need to access the Safety Data Sheets available in the workplace chemical register and find the following information: data on the accepted exposure levels of the substance and its by-products routes of entry of the substance into the body (inhalation, absorption or ingestion) the levels and physical form of the substance in the workplace or the likelihood of the worker coming into contact with it (this may require the use of measuring equipment) the amount of time the worker spends in contact with the hazardous substance the safety precautions taken to contain or prevent exposure to the substance which reactions or processes the substance undergoes in the workplace and whether these may produce other hazards. 56 After checking all of these points you must decide if the risk is acceptable, or if change is required to minimise the risk. Further information on hazard control is provided in the following chapter. 57 Laboratory Safety Checklist Laboratory Date Time Auditors Y/N General Safety Aspects Is t h er e t h e ap p r o p r iat e n u m b er o f t r ain ed f ir st aid p er so n n el o n sit e? Are the first aid cabinets accessible, of the correct type, and up to date? Is laboratory signage correct? Is suitable personal protective equipment available, and properly maintained? Are the staff trained in laboratory safety procedures? Is there an accident incident reporting system in place? Are all the standard operating procedures for the laboratory readily available, and are they followed? Comments Y/N Housekeeping Are the floors clean? Are there any trip hazards or old equipment lying on the floor? Is the shelving the correct height and stable? 58 Are the walkways clearly marked and free of obstruction? Y/N Environment Are appropriate waste management procedures in place? Are wastes segregated and stored correctly? Are wastes correctly labelled and documented? Is there storage and disposal of broken glass and sharps? Are appropriate waste management procedures in place? Comments Y/N Fire Are suitable fire extinguishers fitted and are there the appropriate number? Are the locations of extinguishers accessible and well identified? Have all extinguishers hydrants and hose reels been checked in the last 12 months? Are all built in fire protection devices unobstructed and operational? Are the staff trained in the use of fire fighting equipment? Is emergency lighting install? Is the emergency evacuation plan displayed, understood by all, and practiced regularly? Are suitable fire extinguishers fitted and are there the appropriate number? Comments Y/N Egress Are all emergency exits clearly marked and unobstructed? Are exit doors unlocked? 59 Is the number of emergency exits appropriate? Comments Y/N Manual Handling Have all personnel been trained in correct manual handling and lifting techniques? Are lifting aids and trolleys readily available for any devices requiring them? Comments Y/N Emergency Procedures Are all workplace emergency procedures clearly outlined and known by all personnel (fire evacuation, spill procedures etc.)? Are all emergency teams in place and trained in their duties? Is there a display of emergency evacuation plans with appropriate you are here sign indicating a method of egress? Comments What other areas of the TAFE laboratory should be checked in a safety audit? 60 Open ended project You have been working in your chemistry class and laboratory class towards an understanding of basic concepts in both the laboratory and chemistry, This task is designed to enable you to show your competence in both areas. You are to devise a simple laboratory project that will allow you to separate a mixture of sand, salt and sawdust and provide the percentage composition of the original mixture. You will be guided in class by your laboratory teacher and also you chemistry teacher. Requirements: 1. Submission to your teacher of a flow chart showing the general laboratory procedure 2. Identification of the physical And/or chemical properties you will use to make the separation 3. A completed laboratory request form for each practical session 4. Completed 5 minute risk assessments for each practical session 5. A work journal indicating how your ideas changed each session 6. A log book that records your data in a scientific manner 7. A written report following the format provided by your teacher You will be required to submit a report at the conclusion of the project. The following questions could be useful as you design your project: What properties of each component could be useful for separation? What equipment will you require for the separation? Is it readily available in the laboratory? What hazards exist in your separation procedures? What SDS will you require? Do you need to know the original mass of the mixture? How many sessions do you need for the separation? Are there other methods that could work? Why did you choose a particular method? Why is it important to have a logbook for your data? 61 Basic Arithmetic These exercises are designed to give you practice in the basic mathematical concepts required for successful completion of the course. The maths is generally not difficult but the application of the techniques to the chemical world may challenge even the best mathematician . Lots of practice will ensure you are competent and therefore able to successfully complete the assessments. 1. Use of the calculator 2. Estimation 3. Rounding 4. Order of operations 5. Scientific notation 6. Directed numbers 7. Significant figures 8. Substitution into a formula 9. Rearranging a formula 10. Basic graphing 62 1. Use of the calculator All calculators operate slightly differently but all should give the same answer for a particular calculation. If the answer is not correct then it is most likely that the operator, you, has incorrectly entered data or not followed appropriate mathematical logic. You should know how the following functions operate on your calculator square root log 10 (normally called log or log10) 10x (often on the same button as log10) memory (store, add, recall) EXP for scientific notation The best way to work our how your calculator operates is to read the manual…but they are very thick and this will most likely not occur. The next best way is to try some calculations that you know the expected answer. Exercise 6 +2 x 3 = (12) 5-4 x 3 = (-7) 16 x 4 + 2 x 3 = (70) 63 2. Estimation of result The calculator result is only as good as the operator ie if you enter an incorrect number or do not use correct mathematical logic the answer will be wrong. You should have an idea of the expected answer, not just trust the calculator. Basic process for estimation 1. 2. 3. 4. Round all numbers to one non-zero digit Calculate the values inside any brackets and round the results. Cancel out any zeroes where possible. Calculate estimate. Example Estimate the answer to the calculation from Example 1.2. (63.8 1.94 ) x 0.0547 0.626 x 10 1. Round all the numbers (60 2) x 0.05 0.6 x 10 2. Calculate inside the brackets and round result. 60 x 0.05 0.6 x 10 3. Remove spare zeroes. 6 x 0.5 6 x1 4. Calculate estimate. 0.5 (the exact answer was 0.541). 64 1. Choose the best approximation A, B or C for these calculations Calculation Approximation A B C 6.93 x 11.2 7.76 77.6 776 7.82 x 5.03 39.3 393 3930 0.31 x 0.186 5.77 0.577 0.0577 5.91 x 21.14 11.9 119 1.190 0.00467 x 3.175 0.0148 0.00148 0.148 426.8 x 0.507 21.62 216.2 2.162 Obtain an approximate answer to each calculation and compare it with the exact value using your calculator a) 72.9 + 8.473 b) 0.0417 + 1.38 + 0.00209 c) 324.1 – 20.69 d) 82.01 + 3.97 -70.16 e) 0.003 x 0.0206 65 Now try these (i) 0.112 x 25 .3 = 12 .5 (ii) 24,300 x 16.8 = 8.314 x 298 iii) (23.93 181 .69 ) x 0.123 77.7 = 87.6 1.45 66 3. Rounding To round off to a stated accuracy the last figure to be retained is corrected depending on the digit which follows. A typical rounding system states that if the following digit is 5, 6, 7, 8 or 9 then the last figure is taken up one. Example Round off correct to the nearest whole number 2463.62 2464 Round off correct to two decimals places 7.2048 7.20 Round off correct to the nearest thousand 849801 850000 Exercise 1. Round off to the nearest whole number 2344.62 16.403 7.9 0.735 829.99 2. Round off correct to the nearest figure as shown in brackets) 6.4137 (2 d.p) 36.45071 (3 d.p) 0.003682 (4 d.p) 5.20196 (2 d.p) 463.9 (tens) 8 420 (hundreds) 46 375.9 (hundreds) 68 420 (ten thousands) 4 724 361 (millions) 89 840 000 (10 millions) 67 4. Order of Operations The rules for order of operations are: 1. Brackets first 2. and from left to right second 3. + and – from left to right third Exercise 1. 5 x 4 - 1 = 2. 6 + 10 2 = 3. 27 - 4 x 2 = 4. 2 x (3 + 6) = 5. 6 x 4 2 6. 3 + 4 -2 = = 7. (2 + 3 x 6) + 1 = 8. 4 x 2 + (3 + 1) = 9. 24 4 2 = 10. [(3 + 2) + 4 x 2] + 2 x 2 11. 52 4 8 = 12. 63 63 = 13. 3x 2 3 3 = 14. 8 2 1 5 2 x2 = = 68 15. 4 24 6 64 8 = 16. 16 (4 x 2) 56 7 = 17. 4 4 x8 = 18. 122 52 = 19. 12 – (20 – 3 x 6)2 20. 13 31 2 x3 2 = = 69 5. Scientific Notation Scientific notation is a method for writing very large and very small numbers in the form of a number between 1 and 10 and a power of 10. Example… Avagadro‘s Number, the number of entities in a mole is a number that the mind has difficulty understanding. 602000000000000000000000 Written in Scientifc notation the number is 6.02 x 1023 If the index number is positive it indicates that the number is large and the decimal point has been moved right to left If the index number is negative it indicates the original number is small (less than 1) and the decimal point has been moved left to right Exercises Write in scientific notation 1. 720 000 2. 15 000 000 3. 896.5 4. 8076 5. 0.005 6. 0.000 001 3 7. 0.000 009 8. 10 100 000 9. 0.000 246 10. 21 000 11. 32578.3 12. 0.000489 70 Write the original number for 13. 5.2 x 106 14. 2.015 x 10-3 15. 4.6 x 104 16. 1.11 x 1011 17. 3.33 x 10-4 18. 3.487 x 103 19. 8.47 x 10- 5 20. 7.010 x 10 4 21. 9.02 x 102 22. 1.587421 x 104 23. 4.59 x 105 24. 3.574 x 10 -3 25. 2.0846154 x 10 4 71 6. Directed numbers To multiply or divide Two positive numbers give a positive number Two negative humbers give a positive number A positive and a negarive number gives a negative number 1. 6 + 2 (-2) = 2. (-3) + 3 = 3. (-5) x 6 = 4. -15 5 = 5. -8 x -3 = 6. Given a = -1, b= 2, c = -4 d = -3 Evaluate abc = d2 = a3 = a+b+c+d = 2b c = ab – cd = -(-d) = 72 7. Significant Figures Significant figures are defined as follows: 1. All non-zero digits are significant 2. Zeros at the end of a whole number or at the beginning of a decimal are not significant 3. Zeroes between non-zero digits are significant 4. Zeroes at the end of a decimal are significant Examples 1. 34 100 has 3 significant figures 2. 6010 has 3 significant figures 3. 0.0042 has 2 significant figures 4. 0.0380 has 3 significant figures Exercise 1. Give the number of significant figures in each of these numbers 478 200 4 606 0.01003 3000 863.9462 2. Rewrite each of these numbers i) correct to 2 sig fig ii) correct to 1 sig fig 62 481.69 459 0.0003816 73 0.00204 3.004 86 200 000 0.00004937 2450 74 8. Substitution into a formula Often the calculations you will have to do use provided formulae which are supposed to make the process of getting the right answer easier. A formula is simply a calculation where the numbers are replaced by symbols. In substitution the pronumerals are replaced with numerical values and the expression evaluated An application of this is the formula for moisture content in Example 1.1. EXAMPLE 1.1 You are analysing soil for its moisture (water) content. You weigh out soil into a basin weighing 75.2826 g, until the balance records a weight of 85.9837 g. After 2 hours of drying, the basin and dried soil weighs 82.5832 g. m md x 100 Moisture content (%) w m m b w where mb is the mass of the empty basin = 75.2826 md the mass of the basin with dried soil = 82.5832 mw the mass of the basin with wet soil = 85.9837 85 .9837 82.5832 x 100 31 .78% Moisture content (%) 85 .9837 75 .2826 Other formulae often used in the laboratory include: C1V1 = C2V2 C1 is the concentration of the first (more concentrated) solution V1 is the volume of the first (more concentrated) solution C2 is the concentration of the second (diluted) solution V2 is the volume of the second (diluted) solution C the dilution equation m V a concentration equation C is the concentration is g/L, m the mass in grams V the volume in L. 75 Exercise Substitute the given values and find the variable indicated. V = E – IR a= . P = 2(l + b) C= πd A = 2(lb + lh + bh) Find A when l =5, b = 8, h = 13 A = ½ h ( a + b) Find V when E = 4.61, I = 0.78 R = 5.31 uv . u + v Find a when u = 10.82 and v = 7.38 Find P when l = 38 amd v = 7.38 Find C when d =32.6 (check your calculator for π) Find A when h = 39, a = 20, b= 23 76 9. Rearranging formula to solve equations If the unknown in an equation is not the subject of the formula than the formula must be rearranged in order to obtain an answer. The process is simple as long as the rules are followed: Equations may be simplified and solved by: 1. 2. 3. 4. adding the same number to both sides subtracting the same number from both sides multiplying both sides by the same number dividing both sides by the same number Example x + 8 =4 (to remove the 8 we need to subtract 8, but from both sides) x = 8–8 = 4–8 x = -4 6 x d = 42 (to remove the 6 we need to divide both sides by 6) 6 x d = 42 6 6 d =7 Exercise Solve the following equations 1. c + 18 = 13 2. t – 8 = - 8 77 3. 4a = 2.4 4. 8 t = 4 5. y – 2.8 = 0.6 78 The same process can be used when substituting into formula Example 1 C m V rearrange to make m the subject of the formula In order to remove the V we need to multiply each side by V CxV = m xV V CxV=m Example 2 C1V1 = C2V2 rearrange to make V1 the subject of the formula In order to remove C1 from the left hand side we need to divide both sides by C 1 C1V1 = C2V2 C1 C1 then V1 = C2 V2 C1 Exercise Rearranging the following formula to make the symbol in brackets the subject. (a) C m (V) V 79 (b) C1V1 = C2V2 (C2) (c) Tc = 0.556Tf – 17.8 (d) C (Tf) m (m) V 80 10. Basic graphing techniques Graphs are one of the clearest and most useful ways to express results. The basic graph is drawn by hand and should follow the following rules: Graph should have a title Graph should have a scale for each axis that is easy to read and interpret and is labelled with the appropriate units Data points should be clearly marked either with a X or סּor something similar A line (or curve) of best fit should be used to identify the trend A more advanced method of determining an unknown value is to work with the equation for the line. This will be dealt with in a later resource. PRESENTATION OF LABORATORY DATA Purpose This exercise examines different formats for the presentation of numerical data. Preliminary information Consider the following pilot plant data : At 12:23 pm the pressure in the vessel was 123.4 kPa. The stirrer was then switched on and the special catalyst was added. Readings of pressure were taken for the next two hours and the following data collected: 12:24 pm 125.6 kPa; 12:25 pm 126.7 kPa; 12:26 pm 127.9 kPa; 12:28 pm 130.1 kPa; 12:30 pm 131.6 kPa; 12:32 pm 135.6 kPa; 12:34 pm 135.1 kPa; 12:41 pm 133.6 kPa; 12:44 pm 129.8 kPa; 12:54 pm 127.6 kPa; 12:59 pm 126.3 kPa; 13:11 pm 125.9 kPa; 13:54 pm 123.8 kPa; no change thereafter. Procedure 1. Organise this data as a table with columns for Time, Elapsed time (min.) and Pressure (kPa). 2. Organise this data as three graphs, each with Pressure on the vertical axis and Time on the horizontal axis. The graphs must have the following formats: • graph 1 — time plotted 00:00–24:00hr and pressure 0–200 kPa. Join the dots. • graph 2 — elapsed time plotted 0–100 min. and pressure 120–140 kPa. Join the dots. • graph 3 — the graph which best eliminates the faults of (i) and (ii) and is fitted with a smooth curve (curve of best fit). Questions 1. Why is a graph so successful in displaying numerical data? 2. Why is graph 1 inferior to graph 2? 3. What information is conveyed in graph 3 about the process? 4. Can you suggest a sensible tactic for deciding how to choose axis dimensions for plotting any set of data? 81 Now try these graphing questions a. The following results were obtained from an experiment in which the absorbance of various solutions was measured. Concentration (mg/L) Absorbance 50 100 150 200 250 0.13 0.28 0.25 0.53 0.64 1. Plot the data on a graph to show the absorbance as a function of the concentration 2. An error was made in one of the readings. Circle and reject the outlying value 3. Draw a line of best fit using only the reliable data points 4. Find the concentration of a solution with an absorbance of 0.2 5. What would be the absorbance of a 160 mg/L solution b. During the expansion of a particular mass of gas at constant pressure, the following readings were taken Volume (mL) 400 Temperature (oC) 100 600 150 800 1000 1200 1400 1600 200 250 300 350 400 1. Using volume as the vertical axis, plot these points and draw a straight line through them‘ 2. What was the volume when the temperature was at 325 oC 3. At what temperature was the volume 520 mL 82 General Revision of Concepts Given the following data and formulae, calculate the values of the unknown, reporting the result to an appropriate number of significant figures Formula Data (a) C1V1 = C2V2 C1 = 1.2 g/L, V1 = 5 mL, V2 = 250 mL (b) PV = nRT P = 1.024 x 105, V = 0.234, R = 8.314, T = 298.2 (c) Tc = 0.556 (Tf – 32) Tf = 213.3 (d) (e) C 8000 (b 2a) V C1V1 = C2V2 b = 65.2, a = 21.3, V = 10.0 C1 = 1000 mg/L, C2 = 50 mg/L, V2 = 250 mL 83