Chem 325 Lab Final

In case of a chemical spill to your eyes, you should use the eye wash station continuously for

15 minutes

You notice that your TA is looking pale, and then you see him collapse on the floor. What should you do? Select all correct answers

Stay with your TA to monitor his status, and send someone to report the incident using the red emergency phone in the hallway. Safely stop all experimentation. Calmly wait for UD Public Safety to arrive and assist.

Thin Layer Chromatography (TLC)

A type of chromatography that uses silica gel or alumina on a card as the medium for the stationary phase. use pencil w light pressure

Silver Nitrate Test

Test that uses silver nitrate solution to identify halide ions in solution. a positive test is consistent with the presence of a secondary, tertiary, alkyl halide, but not primary

seperation of a mixture

start w 1:1:1 mixture of benzoic acid, ethyl 4-aminobenzoate, and biphenyl dissolve in diethyl ether and add 5% HCL, then add 5% NaOH dry w sodium sulfate filter pipette into vial and evaporate ether neurtralize both water layers to obtain respective compounds, filter through hirsh funnel to obtain crystals

Thin layer chro

stationary- silica gel mobile- eluent/solvent more polar the compound-lower Rf more polar the solvent-higher Rf

know the location of

red phone, fire extinguisher, fire exit, meeting place

SDS binders

safety data sheets

fractional distillation apparatus

separates liquids by characteristic boiling points; used to purify and separate substances in mixtures

Simple + fractional distillation

seperation of miscible liquids Ptotal=Ppentant +Phexane fractional has more theoretical plates and is closer to being ideal than simple

equivalents how to:

smallest reactant mol= 1 larger reactant mol/ smaller reactant mol Ex: NaOH=.28mol HCl= .31mol NaOH= 1 equiv. HCl= 1.11 equiv.

Broken glassware should be disposed of in the

solid waste

Determine the Rf value of a chromatography band.

start = point of application (your dot) solvent front = top of plate where solvent stops substance = pigment

silver nitrate AgNO3

toxic, oxidizing agent, cause skin and eye burns

DCM

volatile and toxic

Dichloromethane (CH2Cl2)

volatile and toxic

suction filtration apparatus

w hirsh funnel

highly polar compounds (like ionic) dissolve in

water

one ___ rule

glove

theoretical yield

(g reactant)x(mol/g reactant)x(equiv of product/equiv of reactant)x(g/mol of product)= yield of product

g to mg

1 g = 1000 mg

SN2 reaction mechanism

1 step forms w methyl ,primary, secondary carbon strong leaving group (Br-, Cl-, I-, etc) strong nucleophile (generally bearing a negative charge) inversion stereochem same # of double/single bonds

E2 reaction mechanism

1 step forms w primary, secondary carbon strong leaving group (Br-, Cl-, I-, etc) strong base (generally bearing a negative charge) more double bonds (pi bonds) as a result

cyclohexene+ pyridinium tribromide->

1,2 bromocyclohexane (one forward, one back)

equiv. ratio of cyclohexene to pyridinium

1:1

SN1 reaction mechanism

2 step forms w secondary or tertiary carbons strong leaving group (Br-, Cl-, I-) Nucleophile can be strong or weak racemization polar solvent only same #of double/single bonds

E1 reaction mechanism

2 step forms w secondary or tertiary carbons strong leaving group (Br-, Cl-, I-) base can be strong or weak racemization polar solvent only more double bonds (pi bonds) as a result

When do you need to fill out an accident report form?

Any time there is an accident - even if the accident is clearly minor.

How to extract a phenol in a water-immiscible solvent

Aqueous hydroxide or carbonate

Adding pyridinium tribromide and observing orange red color, and if some color persists?

Br2 generated, suggests it was cyclohexene limiting reactant

Which of the following resources provide valuable information regarding the University's safety and hazard directions? Select all correct answers.

Chemical Hygiene Plan Hazardous Material Safety Manual

column chromatography

Chromatography in which the substances to be separated are introduced onto the top of a column packed with an adsorbent (as silica gel or alumina), pass through the column at different rates that depend on the affinity of each substance for the adsorbent and for the solvent or solvent mixture, and are usually collected in solution as they pass from the column at different times

BRRRIIINNNNGGGG! The fire alarm starts to ring in the middle of lab. What should you do? Select all correct answers

Follow the directions of your TA, and calmly and quickly evacuate the room and assemble at the steps of Colburn lab Safely stop all experimentation. Leave your personal items. Your safety is more important than your stuff.

fractional distillation if better bc

Fractional distillation leads to a better separation than simple distillation because the glass beads in the fractionating column provide "theoretical plates" on which the vapors can condense and then re-evaporate, and re-condense, essentially distilling the compound many times over.

You are responsible for safety in lab, and should help others stay safe as well. When using a lab coat or gloves, others will always assume that they are contaminated with chemical or biological hazards, so they must be used only for lab work. Which of the following students would you ask to correct their actions? Select all correct answers.

Gabriel has long hair hanging down in front of his face while working in lab Ryan is wearing his goggles on top of his head when working with a chemical. Jackie walks out in the hallway with her gloves still on to take an emergency call.

determining how many theoretical plates:

If a distillation of a mixture is .3 mol fraction in hexanes in benzene provided that was .7 mol fraction hexanes in benzene, how many theoretical planes (using graph) answer 2 (bc it lands directly on .7) tips: if the chart is a negative slope (like the example) move planes to the right, if the slope is positive, move to the left (if the example was .3 mol and .6 mol the answer would be 1-2 planes bc its not directly on .7 where the line ends up)

In addition to Environmental Health and Safety, the following people are allowed to clean-up blood in the lab:

Only Environmental Health and Safety (EHS) is allowed to clean up blood spills in the lab.

TLC plate if you increased the % of ethyl acetate in hexanes (what would happen to Rf)

Rf would become higher due to molecules attracted to polar stationary phase, by dipole-dipole + hydrogen bonds more polar mobile phase = better at disrupting these

Gloves should only be worn when performing lab work. Which activities is it forbidden to do while wearing lab gloves (regardless of how clean you know they are)? Select all correct answers.

Sending a quick text to tell your roommate you won't be leaving lab early today. Making notes of your time point in lab with your own pen.

percent yield

actual yield/theoretical x 100

Bromination of E-stilbene

air condensor allowa for heating without loss of solvent quench filtrate w sodium bisulfite

E1 reaction

alcohol is a bad leaving group- make into -OH2 to make it better

SN1 reaction

alcohol is a poor leaving group protonation makes it a great leaving group

dry organic layer by adding

anhydrous sodium sulfate

water-jacketed condenser

another name for it

Thermocouple

attached to hotplate helps set temperature

on TLC plate orange color signifies

beta-carotene

6 M NaOH

caustic causes burns

hydrochloric acid (HCl)

caustic, cause burns to skin, eyes, respiratory tract

Sulfuric Acid (H2SO4)

caustic, causes chemical burns

on TLC plate dark green color signifies

chlorophyll a

on TLC plate light green color signifies

chlorophyll b

cyclohexanol

combustible liquid, cause skin, eye, respiratory irritation

limiting reactant

comparing theoretical yield of product, smaller number is limiting reactant *limiting reactant is used up first* (Ex: two reactants, one is left in excess in the reaction, this is NOT the limiting reactant)

Clothing

cover waist down

In the permanganate test

determines alkene group by turning a mucky brown precipitate when oxidized (permanganate has a intense purple color) (reaction shows diols)

Steam Distillation of Cloves

distillation of immiscible liquids by adding h2o to high boiling compounds, it will co-distill as a lower temp reaction: cloves, simple distillation, collect disstillate, extract w DCM, dry organic layer w sodium sulfate, rotovap test- KMnO4- positive w 3 compounds Ferric test only positive w eugenol (out of eugenol, eugenol acetate, and caryophyllene)

thermocouple use with

ethylene glycol

everything is dissolved in dichloromethane except molecular sieves, what technique can you use to remove molecular sieves from solution?

filtration (accept gravity or suction)

Ethanol (CH3CH2OH)

flammable

organic compounds

flammable and can cause irritation

glacial acetic acid

flammable, corrosive, cause severe skin and eye burns. lachrymator

Methanol (CH3OH)

flammable, toxic through ingestion, skin contact, inhalation

1-bromobutane

flammable, toxic, irritating

1-butanol

flammable, toxic, irritating

Diethyl Ether (C4H10O)

flammable, volatile (build up pressure in open containers)

chromatography solvent

flammable, volatile, toxic,

No

food and drink

Recrystallization

growing crystals will self select impurites dissolve in min. hot solvent and cool slowly biphenyl dissolves in methal ethyl 4 aminobenzoate dissolve in ethanol benzoic acid dissolve in h2o impurites act as a flaw and make up a lower and broader melting point

If a hazardous chemical has splashed on your clothes, what should you do?

immediately use the safety shower and then begin to remove all affected clothing.

Finkelstein's test

indicates unreacted alkyl chloride or bromide (CHxCl), using NAI/ acetone, SN2 reaction, formation of a precipitate is consistent with the presence of a primary or secondary alkyl halide, but not tertiary.

silica gel

inhalation hazard

more soluble in dichloromethane in water

ionic

Sodium Iodide (NaI)

irritant

sodium bromide NaBr

irritant

amberlyst 15 ion exchange resin

irritant ( especially eyes)

benzoic acid

irritating to the skin, eyes and respiratory system

biphenyl

irritating to the skin, eyes and respiratory system

ethyl 4-aminobenzoate

irritating to the skin, eyes and respiratory system

addition reaction

less double (pi) bonds as a result

labels

name course and lab section date full chemical name

neutral compounds dissolve in

organic solvents (like diethyl ether)

pyridinium tribromide

oxidizing agent, corrosive, causes severe skin and eye burns

ferric chloride test (FeCl3)

phenols (benzene-OH) form intense colors with Iron (III)

goggles

wear at all times

on TLC plate yellow color signifies

xanothophylls