Think Again! like skill in sports, music or art-docs not come naturally to anybody uccess in each of thcse areas depe nds on discip line, practi ce and tra inin ' In the chemi stry lab, you encounter ncw equ ipment and varied types of chemical materia ls, requi ring training if you plan to usc them sa fe ly Remcmber, details arc importan t in chem istry and not just where numbers and ca lculat io ns arc concerned Chemical names and formu las present a whole new li ngo You have to know these symbols and defini­ t ions to wOI'k in t he lab One leller can mean a lot-chlorine, with on "n," is a toxic ~ sodium chloride, with a "d," is a harmless soil ­ Safety Training Safety is an integral part of work ing in the chcmis try lab, and a respo ns ibility sha reo by studen ts a nd instructors Learning about safety is part of yo ur ed ucat io n; skil ls you gain in the lab will serve you in future careers and in lifc lf nothing else, they will ma~e you a better cook' Be Prepared Where is the lab exit? l: very lab sho uld have ill least two exits Know how to get out q ui ckly in an emergency Never work in on isolated "corner" of a lob; upper-floor windows not count as emergency exits Where is thc nearest p ho nc '! You may neeo fo call for emergency help If so, di al ill or your local cmergency number Do not rely on the cell phone in your book bag­ it may be on fire! • Where is the fume hood? - You'll necd to use it for any no,xious reagent Always use a hood when working with concentrated acids or aqueous ammonia If Ihe chemical has a pungent order, or is a health risk, you need to use a hood Where arc the eyewash sta tion and safety shower? These arc for was hing s~in and/or eyes ex posed to chemicals • Where is the fil'c extin!!uis her? You may need to u~ e it to use small fires Check with your instructor on guidelines for using an ext ing ui sher So m e fires require special treatment Sodium reacts with water, a common ingredient in most fire extinguishers Personal Respo nsibil ity R ule I: Protect yourseln Your mi stakes will likely harm you more than anyon e else Rule 2: Reael the lab manual be lore class Come to lab pre­ pared to work on the assigned ex periment ­ R ule 3: Always pay atte nt ion as yo u work Watch other students; you ar impacted by their mistakes Rule 4: Clean up your own mess You arc a partner in ma intaining a sa fe lab Kevs to a Clean Lab Keep your work space clean and organi zed Wash labware wit h detergent: ri nse with de- ioni7ed or disti lled water; usc a wash bottl e to conserve water; drain excess liquid; a llow object to d ry be fo re stori ng • Shared eq ui pment wash before a nd afte r each use • After each lab se ss ion , return reagents and eq ui pme nt to the des ig nated storage areas X D anger! • Always work with instructor supervi sion Never wor k in a lab alone Iways wear goggles in the lab even ov I' eyeg la sse s: replace contact lenses \\ ith eyeg lasses (ontoct lenses can absorb solvent vapors If you accidentally get chemicals in your eye, the contact lens can actually trap harmful chemi­ cals between the lens and your cornea So, switch to glosses for lob sessions • Wear an apron, lab coat and g loves to limit your chemi ca l exposure and to save c lothing from ch.;mical stain s Select gloves to match the chemicals that you are using in the lob Some gloves dissolve in certain organic solvents Think about what happens when you expose a Styrofoam cup 10 ace­ tone Unless you wont it stained, never wear your favorite new shirt to the lob Wh ile working in the lab, yO U will usc a number of reagents, giving ample chance for exposure to the harmful effects of chem ical s In some cases, exposure will be due to an acc identa l spi ll ur breakage of equipmcnt Other lim­ ited ex posure may come as a result of using the chemicals as directed If yo u can smell a vo tatile chemical, it could hal-m you Your scnse ofsmel l is very sens itive rcfkcting your body's scnsitiv ity to all types of odors Thi s also reflects the efficiency of our biochemistry and explains why we have adverse reactions to minute quant ities of cer­ tain chcmicals Possible Risks of Exposu re Inha ling chcmica l rowdcr or vapor Takc care when working wit h any vo lati le solvents Remember, if you can smell it, it could be harming you Ingesting so li d o r liquid chcm icals by mouth You are not likely to make a meal of chemicals in the lob, but any chemical on your hands or face could end up inside you when you consume food after the lob session • Wear closed-toe shoes and long pants to protect your Icct and legs Punctur ing your skin with a sharp object and po 'sibly inj ecting chemica ls into your body These precautions provide protection from spilled chemicals and broken gloss Acommon source of this type of injury is a chipped beaker, flask or pipet Toke special care when inserting gloss tubing or a ther­ mometer into a rubber stopper; always use a slit-stopper and lubricate the gloss to ease insertion If you have to force it, you may snap the gloss tube and end up inserting it into your hand • Tic back hair and avoid bulky s leeve s that II1tcrfe re with work You also may wont to remove rings and other distraclingJ'ewelry that may lessen your grip on beakers, test tubes on other equipment Some jewelry may be damaged by lob chemicals Do not store book bogs, cell phones or other electronic gear on the lob bench They can interfere with your work space and could be damaged by a chemical spill or occident Absorbing chemica ls th rough your skin NEVER handle any chemical with your bare hands Examine all cases of exposure to solid or liquid reagents, and toke the appropriate action to treat the harm to your skin Some solvents-for example, DMSO (dimethylsulfoxidel-easily pass through the skin and into deeper tissues Food and drink shoul d not be brou ght into the lab This greatly enhances the chance that you will accidentally consume lob chemicals along with Ihe drink or snack, Wa sh your hand s alier each lab sess ion bcfi) rc leaving This will greatly reduce your risk of harmful exposure to chemicals You definitely not wont to have lob chemicals flavoring the burger and potato chips you have after lob! FIRST AID C heck with instructor for local guideli nes Burn from hot hlb wa rc: M inor: App ly co ld water SC I-io us : Contac t medica l help Cut from bro ken glassware: Heating Labware U~c to ngs to handle la bwarc whil e it is hcatcd by a burner o r hotplate All ow the item to coo l to room tem peraturc before weighing Hot lob items not look hal, Hot ilems create air currents that alter the reading of a balance Liq uid Reagent Cover the beaker with a watch t!l ass Use " bo iling stones' to promow smoot h bo iling Flam mable solwnt : Ta ke care when heatin g \\ ith a hot pl ate; avoid usc of ga s burner Handle test tube \\ ith wire-holder Heating a liquid is not a race; overly rapid heating can couse the solution to erupt into a boil, termed bumping, usually resulting in the liquid spilling onto the hot plate or burner and the lob bench top, and soaking your notebook, etc Solid Reagent Use a weigh ll1g di,h on the balance Cover the dish to prevent loss sp ill s o r contam inatioll Always record lob data in on organized notebook, including the number and unit Mi no r: Wash with soap, apply antiseptic ointment and ster iIe bandage Seriu us: Cont rol bleedi ng by applying prcssure \\ ith sterile pad; contact emergency medical help Be especially aware of the danger of chipped beakers and flask s Also, toke core when washing gloss labware; it gets slippery and is easily dropped Skin-exposure to a chemical : Ri nse wi th water; i I' condition develops contact medical personnel Feel ing Jightheaded or passing ou t: Move affccted person to fresh air outside the lab ; contact mcd ical personnel if the cond ilion persist s This can be a common problem when working with cylinders of compressed gases, such as (0, (0 2- even non-toxic gases such as He and N2can displace the oxygen in the lob Burning cloth ing: Do nut panic; drop to the flo or and smother the flame ; use safety -hower to treat burn ; tact emcrgcncy mcd i al personnel DO NOT use a fire blanket; these only complicate subsequent medical treatments for burns Summary Good lab planning and prevcntion of accidents is the bcst fi rst aid Do not be hcmic! Dcal \\ ith cuts and minor chcmical c-.posure Call emergency personne l for anything that is major Some chcm icals arc toxic; all ca n cause harm if used incorrectly Lcarn about reage nts bc forc usin g them in an experiment Rea d your lab manua l and textbook, and talk to you r instruc tor Ir in ubt, ask q uestio ns! : t - -HEA LTH - Deadly - Extreme danger - Hazardous - Slightly Hazardous o - Normal material F'IR E HAZARD Flash Points: - Below 73g F - Below l00g F - Above l00 F, Not 2002 F Exceedi ng - Abo ve 200IlF 0- Will not bur" W- Radioactive Of - May detonate - Shock and heat may detonate - Violent chemica l change - Unstable if heated - Stable NFPA Hazard Codes (National Fire Prevention Association) (Highlights major chemical hazards) J T Baker System BLUE healt h hazard Store in secure (lockcJ) poison arca EX: cYllllides, lIIeI"CIII:I' Chemi(als that are toxic if inhaled, ingested or abl{)rbed through the skin X RED fla mma ble hazard Storc in a '" nammablc IiCJu ids" EX: (IC('(Olle, orgllllic soillellfs storage a rca Chemicals that easily ignite; also, explosion hazard Organic Compou nds - G eneral Ru les Non-polar compounds (EX: hexane an d ben.rcne) are soluble in non-polar organic solvents, but insoluble in water reactiv ity hazard tore in an area iso latcd /i·OIll EX: rellcth,c lII elal." clllciulII or sodiulII llall1lllabl cs and cOlllbustibles May read violently with air, water or other substances cOITosivc hazard Store in corrosion-resistant area EX: c(l// cellfrale{lacitl., 111111 bases Ac id s and bases eparalcd Oxidi zing acids separa ted fro m organic acids Chemicals that read with skin or other exposed tisSue, Organic Solvents Boiling pf 79 "C ethano l methanol 65 \IC acctone 56 " isopropanol R2 (lC benzenc 80 III "C toluene X X May be stored in gcneral storage IJIAG ONAL incoillpatibies STRIP E Storc with ca ut io n V Reads with other materials in that A storage group; store each one separately ocelole [hloride nilrole bromide per[hlorole iodide [hlorole On your cl oth ing or skin sse,s the ri 'k prescnted by the chcmica l Dilut.: solu­ tions of 1110st reagents not present a major health risk rhink about a M NaCI vs a 10.0 M IIN O, rhe f'()fIller is harm less: the latter can cause major skin and clothing damage o If needed, renwvc a rreeted artic le of clothing; was h exposed sk in with water and apply first aid Treat pn'!11ptly to minimi/c hann I f a large r area is exposed use the safCty shower, then apply first aid Aftcr rirst aid, follow up with professional medi ca l treatment fluoride lullole (orbonole ,ulfide pholphole hydroxide [hromole oxide lorm hydroxide melo~, inlol inlol inlol inlol I inlol inlol Inlol Inlol inlol insol insol Inlol insol insol Inlol insol insol Flame test: C haracteristic colors of iOIl ill a flame polossium, rubidium, cesium copper (ozure), leod, arsenic, selenium copper (emerald), borium (yellowish), zinc (whitish) sodium lithium (cormine), stron~um (\Corlet), calcium (yellowish) C'ommerciul l{cagcn1 CHEMICAL SPILLS You not wont to track through any spill; it may dissolve your shoes!! Molar moss (g/mole) 46.07 polar 32.04 polar 58.08 polar 60.11 polar 78.12 nonpolar 92.15 nonpolar alkali violet: blue: green: yellow: red: Acids Summary Always consider the property before you use a chemical If two chemicats react, for exam pte Het and ammonia, you defi nitely not wa nt to store them on the same cabinet shelf! On the floor or bench to p o For small spill s: Wear glmcs, neut lil.c acid 'base; absorb usi ng paper towels and di scard in a labe led b"g Make sure the Ioves arc resistant to thc chemical that is >pilled o La rger spills: Notify the instructor; wear gim es and shoe protectors, use a ~pill kil des igned for the chcmi­ ca l Your lab should be eq uipped \\ ith tlwsc item s Clean up all spills promptly to prevent further accidents Density (g/ml) 0.79 0.79 0.79 0.79 0.88 0.87 Properties of Inorgan ic Salts Aqueous Solubili ty X GREEN or no serious hazard ruzn ' Liquid Solubility Rule: "Like Dissolves Like" Wate r "The Universal Solvent" boiling point: 100.0 "C freeling point: 0.0 "C density: 1.00 g/mL at °C molar mass: IR.O 15 g vapor prcssure: 23 mm Il g, 25 "C Polar compo unds (EX: amines alcohols, ol'ganic acids) tend to disso lve in water I I SP ECIFIC HA2:ARI) - +" Oxidizer Acid ACID Alkali ALK Corrosive COR Use NO WATER Material Safety Data Sheet (MSDS) A detail ed description of ev ryt hing you eve r want to know about a chemica l So, whether yo u are using water, mercury or sodi um chloride, you ca n find out how thi s material should be handl ed Copies ofa MS DS should bc in the lab for all th e chem­ ica ls you arc usi ng Consult th is material if you have any qucstions about the risk associated wi th a chemica l Chemical S to rage C od es Chemicals in the samc color group ca n norm ally bc stored toget her; exceplions noted on the label "Wast~" is a term \\ ith specific mcaning in the chemi­ cal community r cderal , state and local laws mandate how chemi , u' labs hand le the excess sol vents and othc r eh mi cal s th arc ge nc ted by ch emi sts Chemi ca l waste may or may not be hazardous I ollow thc instructor 's diredion s for di sposal of all lab material s Most chemi cals SllllUld not bc pourcd down the drain You r insti tution may be penali zed by fcdera l authorities if waste is no t hand led properly by you and other students Mistakes as simple as unlabelcd waSIl' bottles can rcsult in substantial fin cs All toxi metals and halogenated so h ents must be col­ lected for proper di sposal loxills may be ac tive at very low levels 1: 100 I part per hund red ( % ) '/100 1: 10" I pa rt per million (ppm) '/1.1"".'"'0 1: 10' I part per billion (pp b) '/,.0'>1•.1100.""0 1:10" part per trillion (ppt) '/,.00" " ".,.•0 Waste Prevention: Usc only the requ ired amount of reagent Excess mat rial cannot hc returned to rcagcnt jar; it is "waste," Reagcnls arc often cxpensi vc, so ­ servation helps keep lab costs 10\\ A spot plat ' is an excellent means to co nserve reagents GE NE RAL RULE : When in doubt, coll ect all ,olu­ tions used in the lab in labe led waste bottles Make slire that any chemical that is poured into thc , ink is not going to react in the ,cm:r lin e or contribute to pollu­ ti on Most loca l water-treatmcn t faciliti es mon itor water from school labs Remember- if you "sink it" today, you "drink if" tomorrow! We only borrow wafer for home use, drinks and food preparation Dilution is NOT the solution to pollufion, hydrochloric, IICI 11.6 M pungent 16.0 M o.xidiLcr nitrie, IINO sul furie,II,SO, 18.0 M dehydrating agcnt acctic 6.27 M 17.4 M glacial acetic phosphoric 14.7 M Safety note- oxidizing acids should not be stored or mixed with organic acids, Bases NaOl1 and KOII, hygroscopic pellets Commercial Ilca ~cnl NaO l1 19 M aqueous ammonia 14.X M pungent Common Chemical Reagents & Molar Mass oxygen gas (), 32.00 g mol nitrogcn gas Nl 28.02 glmol hydrogen gas II , 2.016 g,mol chlorine gas CI, 70.90 g mol graphite or charcoal C 12.0 I g mol Properties of ir Roughly 80°" N" 20"·' 0, Water contcnt, variablc I 4(~ pH Kev equations pl l -Iog w [II J pOll - -Iog lo [011 -1 pOIl+pH 14 Water sclf-ioni;ation: pK" 14 pH nge & examples Strong Acid o Strong Acid Base Neutral 10 11 12 13 14 Base H,O H,CO, HAc NaCt NH:Salts NH, Ca(OH), Ac' or COt Salts NaOH KOH Acid-Base Ind icators Com pounds that change co lor as the pll changes Se lecti on: Pick to matc h thc pll ru nge of the sa lt pro­ duced by a titration or other process Name Range I­ Acid-Base Color 4.0-5.6 YOIJ I~IJJ-blue m ethyl red 4.4-6.2 red- YOIlbJJ phenol red 6.4-8.0 y.sdJ:.IJJ-red thy m ol blue 8.0-9.6 YOIHc.IJJ-blue phenol p hthalein 8.0-10.0 C!", ~~"'U mcresol green ,-red - - _. tv ¥ :l ~ il ;g ~ , ~ "5 g ~ '" ~ ,' - - - - , 6.022 x 1023 mol-I Avogadro's Number, N,,: 1lO x 10-' kg Mass of electron, me: 1.673 x 10-27 kg Mass of proton m,,: 1.675 x 10- 27 kg Mass of neutron, mn: 6.626 x 10-34 J S Pl anck's Constant, k: 1.602 x 10- 19 C Electron charge, e: Faraday Constant, F: 96,485 Clmol Idea l Gas Constant, R: for gas calcu la tions: 0.082 L atm mol-I K- fo r energy calcu lati ons: 8.314 J K-I mo l-I 2.9979 x lOx m/s Speed of light: Standard temperature and pressure (STP ): I atm and "C Vo lume o f Ideal Gas at STP: 22.414 Llmo l Typi ca l room tempe rat ure: 20 25 "e co ~ -'L "1'!I~ " E z Cha rge OH C0 HC0 N0 N0 O2 P O SO 503 C IO NH 1­ 2' 1­ 1­ 1­ 2' 3' 2' 2' 1­ 1­ hydrox ide c a rbonate bicarbonate nit rate nitrite peroxide phospha te su lfa te sulfi te perchlorate ammonium Molar :\Iass 17.01 g/mol 60 01 g/mol 61.02 g/mol 62 01 g/mol 46.01 g/mol 32 00 g/mol 94.97 g/mol 96.97 g/mol 80.07 g/mol 99.45 g/mol 18.04 g/mol PREPARING A SOLUTION How to dispense liq uids Cho ice of cquipml.!nt de p~ n d s on desi red prec ision LJ c a ,ma II beak.er to obtaIn the needed amount fro m the reagent bottl e Try to ovoid toking extra reagents Imagine if every student in the lab used times as much reagent as needed Usc a funnel to tran~fc r to a il a, k Otherwise, you get more material on the outside of the flask ond table than on the inside, where it should be -'IIi"_ Note the precision of the volume measured by each piece of equipment A flosk, buret and graduated cylinder all measure volume with different precision How to d ispense solids Use a we ighi ng dish to hold the sa mple; dispense fro m a beaker us ing a spatul a not fm m the reagent bottle (thi s may contaminate the ent ire supply) Use a funnel 10 transfer in to bottle or fl ask Be aware of the effects of air currents in the lab, especially if you are working in a fume hood Your powdery solid could end up spread all over the table, instead of in your beoker, where it belongs How to use a pipet Step I: Insert the tip of the pipet into the li quid Use a suct ion bulb to draw liqui d into the pipet past th.: des ired "mark" on th stem of the pipet Step 2: Qui ckly replace the bul b with) our finger; ca re­ fu lly rel ease the vaCU UI1l and all ow thl' liqui d to drain fro m the pipet Step 3: lOp the now at the deSIred ··mark." Step 4: Ins'I1 pipet into the nask and re lease th e liquid Under no circumstances should you ever pipet using mouth Ttion, even if you ore pipelling water or hormless solutions T is creates a bad habit, and suddenly, while not thinking, you have jUlt pipetted mouthful of sulfuric acid Ho\\ to use a balance Manual triple-beam and electronic bal ances arc used in the lab Clean the pan with a so n brush; if the pan is stainecl \\ it h the assistance of the instructor, remove and clean the pan Zero the balance before usc; oth erwise, all of your mass data wi ll be incor r~et Usc a we igh ing dish to hold the sam pl e; pre-weigh the dish add the sampl , re-welgh sam ple and dish; dcter­ mi ne sampl e mass by dlffe rence Your dota will be meoningless unless the balance is properly zeroed EX: If tile l/ish h as a IIIlIS.\ /If g 01111 th e slIlIIple pIlls c1i.' " " 11' lIlIIlI.' \ /I{6.5 g t"e lIIass of t"e sample i, 6.5 g - 5.0 g = 1.5 g, NEVER weigh chemicals directly on the balonce pan Clean up any spilled chemical on or oround the bolance before you leave it NEVER weigh a hot object-the heot generates oir currents that alter the measurement How to use a gas burner ccurciy nect bu rner to the gas supply with rubber tubI ng fa dua lly inc rease gas flow and I!!nite the name Adjust the air/gas mix to gi \ c a quiet, hot name The size o r the name sh ou ld "fit" your applica­ tion mall te,t tu bes only need a sma ll namc Be especially owore of the risk of burns when working with a burner ond hot labware How to use a hot plate Pl ug the hot plate cord into the electrical outlet Adjust the sett ing to gi\'e the tcmpcrat un: req uired for your app li cati on Use tongs to manipul ate the lab \\are on the hot pl ate Clean the hot p lat~ surface after it cooled Do not simply set it on "high" and then forget obout it The sur­ fate tan get hot enough to melt lead Take core when using flammable solvents on or oround a hot plote If spilled on the hot ceramic surface, ~ can ignite Lab equipment is delicate and expensive; learn to usc it correctly Ask for assistance if you need he lp Disciplined troining is required for any octivity requiring skill in • science, sports, music or art You not naturally serve aces at Wimbledon or shoot under por ot the U S Open Championship Do not usc worn or frayed electrical cords This lead to dongerous electric shocks and the igniting of other flammoble materials in the lob If you hove equipment with these problems, contoct the instructor Be aware of the risk of static electr icity it may harm computers and can ign ite nammablc so lve lll This is more of problem in dry climates ond in labs with cor· peted floors (in the labs or in attoched hallways) Watch out for chipped or cracked glasswa re; disca rd in the glass-recycle box Ask your instructor for guidance with disposal of any damoged lab equipment Thermometer: Usc "non-mcrc ury" for routine work Unless you are in need of measurements over 120' C, you should never work with a mercury thermometer in your lab Refr ige rato r: Store chem ica ls in sealed contai ners; not store food with chem ica ls Always follow your instructor's guidance on storing items in the - lob refrigerator Co mpressed-gas cytind ers: Secure to a wa ll or bench; fa lling cylinders cause se rious inju ries If you need to use this type of equipment, your instructor will troin you in the use of the valves and regulators Check for possible chemical hazards associated with the gas; EX: CO, CO 2, H2, O2, etc Chemical reagents arc often dispensed as solutions You may need to prepare a solution from scratch or prepare dilutions of"stock" solutions Thc most common solu­ tion concentration unit is molarity, M A 1.0 M solution of NaCI contains 1.0 moles of aO in 1.0 Liter of solution The moles of material in a given V of solution of molarity, M, is given by M x V EX: Il),oll llispellse 0.50 L (!lll 1.0 1\1 Na CI solu­ tiOIl , y ou (l rt! wor killg wit": 0.50 L x 1.0 mol Na Ci/ L = 0.5 m oles ofNlICI C enera l C uidelines Use volumetric glassware; add reagent dissol\e in some solvent and then dilute to the "mark" on the nasI with additional so lvent Organ i7c the essential information before starting to prepare a so lu tion When you are standing at the balance is not the time to ask yourself, "How much of this stuff I need?" Liquid reagent - you usually d~termine the mas from the dispe nsed volumc and dens ity of the liquid: mass (g) = vol (mL) \ densif) (g/mL) Ifyou nced the exaet mass of the liquid reagent weigh out the desired quantity using a ba lance Dilute Sol utions from Stock Step I: Step 2: Step 3: Step 4: Se lect volume, v-d if, and deSIred concen trat ion c-di! Deteminc v-stock of re~gent of concentration c-stoc k Use this equation to ca lculate v-stock: , -dif ) c-di l = v-stoc k xc-stock Add enough solvcnt to dilute v-stock in a volumetric nasI of volume ,-di l Dil ute Sol utio ns from Pure Rea ge nts Step I: 11 data has ~ "lI um ber" and ~ "unit.'· Metric Conversions Mass I kg = 1,000 g To convert "g" to "kg": divide by 1,000 I mg = 0.001 g To convert "mg" to "g": divide by 1,000 Size I mm = 0.001 m To convert "mm" to "m" : divide by 1,000 I cm = 0.0 m To convert "cm" to "m": dividc by 100 Vot ume I mL = 0.001 L To convert "mJ :' to " J :': divide by 1,000 I,OOOmL = IL To convert 'T' to "mL": multiply by 1,000 760 mm Ilg = Iatm Press ure To convert "mm Ilg" to '"atm": divide by 760 TemperatureT (K) = T (OC) + 273 15 To convert ''''C'' to "K": add 273.15 Time I hour 60 mi n = 3,600 sec To convert "hI'S" to "min" OR "min" to "sec": multiply by 60 With any unit conversion, it is eosy to use the wrong factor Always double-check before using the data Select the desired concentration, C and volume, V Step 2: Determine the required number of moi