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Final

Full Lab Notes (Covers Everything)

10 Pages
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Department
Chemistry
Course Code
CHEM261
Professor
All

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Description
Ochem Lab▯ ▯ Safety▯ Never pour water into concentrated acid. it is exothermic. ▯ WHMIS workplace hazardous materials information System▯ ▯ heated or dropped. ▯d gas (Class A) explosion because gas is pressurized. explosion if ▯ Flame (Flammable or Combustible) Class B - catches fire at low temperature, may ignite spontaneously, or release flammable gas on contact with water ▯ Oxidizing Material (O with flames on top) Class C - reacts violently and causes explosion when in contact with combustible material- burns skin and eyes upon contact▯ ▯ dangerous) - fatal poisoning substance - immediately fatal upon inhalation, swallowing, or through entering body through skin contact. ▯ ▯ T (toxic) Class D2 - poisonous not immediately hazardous to health, long exposures causes ▯ermanent damage or death, may be an irritant▯ Biohazardous Infection Material Class D3 - serious disease = illness or death, toxin that is harmful to humans▯ Corrosive (Class E) causes sever eye and skin irritation upon contact, sever tissue damage with prolonged exposure▯ may be harmful if inhaled ▯ R Dangerously Reactive Material - unstable, may react with water to release toxic or flammable gas, may explode as a result of shock, friction or increase in temp. may explode if heated ▯ ▯ and therefore are a safety hazard. ▯tible with organic solvents and act as an ignition source ▯ ▯ Calculations; ▯ percentage: ▯ 10% NaOh solution = 100g/L MW = 40g/mol▯ ▯ 100g/L / 40g/mol = 2.5 mol/L ▯ ▯ Techniques: ▯ rinse glassware with wash acetone. allow acetone to evaporate. Heat with bunsen burner or in drying oven or with a heat gun. ▯ ▯ ▯ Washing: ▯ ▯ash with acetone. if it doesn’t work then use 6 M HCl or sodium bisulfite. ▯ Tapered Glassware▯ creates joints from glass. 14/20 joints means diameter(mm) of the top of joint / length of joint▯ ▯ ▯lways set up from the BOTTOM UP▯ Density = weight / volume ▯ ▯ HEATING▯ Liquid with bp below 70C. = Steam bath NOT BUNSEN BURNER CAN CAUSE FIRE▯ Steam bath = heating recrystalization mixture, evaporating, and heating low boiling point solvents at reflux. ▯ Heating mantles used to heat flammable or explosive organic solvents. ▯ ▯ Hot plate. Liquids above 80c. ▯ ▯ ▯oiling stones: used to prevent bumping and ejection of liquids. ▯ Cooling▯ 0-5C Ice and water▯ -20C Ice:salt 3:1 ratio▯ -55C Calcium chloride: ice 1.4g:1.0g ratio▯ ▯75C Dry ice and acetone in a dewar flask▯ ▯ Melting point ▯ is measure as a range.. usually when the first drop of liquid appears and when the whole solid is melted. Pure have a small rance 1-2c while impure have depressed melting point range (larger) ▯alled melting point depression. ▯ Boiling Point▯ The lower the atmospheric pressure the lower the boiling point. ▯ 0.5C CORRECTION PER 10TORR DIFFERENCE FROM 760 TORR▯ FORMULA ▯ BOILING POINT CORRECTION FACTOR = (760 torr - atms. P / 10 torr) x 0.5C ▯ factor + observed bp = correct bp▯ ▯ 1 torr = 1mmHg▯ Solubility▯ hydrophilic = polar water loving because water is polar ▯ hydrophobic = non polar because water is non polar ▯ ▯ NON POLARToluene -▯ ▯ther -▯ DCM -▯ Ethyl▯Aceta▯e —> A▯etone ▯> Meth▯nol/EthanolPOLAR▯er▯ ▯ organic compounds mixed in water can be extracted from water by mixing with hydrophobic solvents such as ethyl acetate. salts and hydrophilic liquids are extracted from hydrophobic solutions using water. ▯ ▯ Drying▯ using pre dried brine, (saturated sodium chloride) sodium sulfate (drying agent)▯ anhydrous inorganic salts are drying agents removed using filtration▯ ▯ Chromatography▯ contains a liquid and stationary phase. In liquid liquid both stationary and mobile phase are liquid. The more a compound will adhere to a stationary phase the slower it will migrate and less it will travel. ▯ Partition = liquid liquid▯ TLC = liquid solid ▯ Adsorbent = the substance that absorbs entities traveling over it. EX. in TLC it is alumina (aluminum oxide) or silica gel. ▯ ▯ Stationary Phase: solid or liquid that entities adsorb onto. ▯ ▯ liquid mobile phase: passes through the column and carrys components at varying rates. ▯ Eluent: the system used to develop the chromatogram ▯ ▯ THE MORE POLAR THE F.G THE STRONGER IT WILL BOND OR ADHERE TO THE ADSORBENT AND THE HIGHER IT WILL TRAVEL UP ▯ ▯ TLC▯ The sample should be dissolved in the least polar (most non polar) solvent it can dissolve in.▯ ▯ Visualization occurs with UV light for aromatics and compounds with conjugation that are UV Visualization can also occur with a TLC stain such as Vanilin or phosphomolybdic acid. ▯ ▯ Rf = retardation (retention) factor ▯ ▯ pure samples will have one spot will impure samples will have more than one spot. This is used to determine identity of compounds by co-spotting. ▯ Column Chromatagrophy ▯ Selecting Eluent ▯ ▯ ▯ Extraction ▯ SOLID LIQUID EXTRACTION▯ often carried out at reflux. Used to leach out compounds from a solid using solubility of desired combined with solvent. ▯ LIQUID LIQUID EXTRACTION▯ an aqueous solution and organic solution are allowed to separate. salts will be dissolved only in aq solution will most organic substances will be dissolved in the organic solution. ▯ ▯ To select a solvent: ▯ - the solvent must be immiscible with phase being extracted (usually water). ex if extracting a salt, a hydrophobic organic solvent must be used that is immiscible with water. This solvent must also have a LOW BOILING POINT. ▯ - MOST COMMON SOLVENTS = diethyl ether and dichloromethane (DCM)▯ Chemically Active Extraction ▯ Recall Brownsted Lowry definitions of Acids/Bases:▯ -Acids are proton donors. ▯ -Bases are proton acceptors. ▯ Salts are cations and anions. result from the reaction of an acid and a base. ▯ you can separate compounds using reverse salt formation. ▯ ▯ ▯ Acidic Organic compound is reacted with a dilute inorganic strong base to form a salt (ex. NaHCO3 and NaOH). then conc. acid is used to acidify salt back into the original organic If the organic compound is dissolved in 20ml solvent. ex. DCM then use half of that (10ml) of dilute base. ▯ ▯ Basic organic compounds with amine f.g. react with inorganic dilute strong acid to form a salt. then reacted with conc. base to go back into organic compound. PH PAPER IS USED TO TEST▯ ▯ EMULSIONS ▯ colloidal dispersion. particles are suspended within the liquid. ▯ -oswirl instead of shaking▯ - add brine and shake▯ - leave for some time▯ - add alcohol, acid or base, ensuring that whatever you add does not react▯ - filter by gravity filtration or using filter aid▯ ▯ ▯ REFLUX▯ carrying out a chemical reaction at boiling point of solvent. Reflux apparatus allows continuous ▯oiling while preventing loss of liquid. ▯ NOTES: ▯ - add boiling stones ▯ - water flows IN LOWER INLET UP CONDENSeR AND OUT UPPER INLET▯ ▯ A standard taper ware drying tube that is filled with a DRYING AGENT SUCH AS ANHYDROUS CALCIUM CHLORIDE is placed at the top of the condenser to prevent moisture from entering. ▯ Addition of reactants under reflux ▯ requires ▯ - lab jack▯ - pressure equalized addition funnel▯ - heating mantle▯ - condenser▯ - stopper▯ - round bottom flask▯ Removal of noxious gas▯ place an inverted funnel onto of the condenser and attach a water aspirator. DO NOT USE VACUUM as it can be strong enough to suck all vapours and solvent. ▯ ▯ ▯ Sublimation▯ CONVERTS A SOLID DIRECTLY INTO VAPOR WHILE SKIPPING LIQUID PHASE ▯ ▯ TWO METHODS▯ ▯ 1 using a sublimation apparatus consisting of a vial and a test tube with 1-2 cm between them. sublimand (solid to be sublimed) is spread into the largest vial and the condensing test tube is filled with ice water. the outer vial is heated on a hot plate. ▯ ▯ filled with glass wool. Watch glass is place on a heating plate. this traps the vapours without being a closed system. ▯ ▯ MAINTAIN SLOW HEATING ▯ ▯ ▯ RECRYSTALLIZATION▯ A PURIFICATiON method because of the selectivity of the compounds that are allowed into a specific crystal lattice. ▯ it is possible because DIFFERENT SUBSTANCES HAVE DIFFERENT SOLUBILITIES IN SPECIFIC SOLVENTS AT DIFFERENT TEMPERATURES ▯ ▯ 1. Selection of a solvent ▯ - good temperature coefficient = dissolve a lot of the substance when hot and little when cold▯ - impurities should be the opposite - insoluble in hot and mod
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