O Chem Lab Final

Front 1

Jones Reagent Test

Back 1

- corrosive

(+) Test indicates: 1 or 2 alcohols, amines, aldehydes, and phenols

False (-) : 3 alcohol

Solution turns from orange to blue-green

Front 2

Bromine Test

Back 2

- Toxic

(+) test indicates pi bonds, alkenes, aldehydes and phenols

Solution goes from brown to clear

False (+) : Dilution

False (-) : Too much reagent

Front 3

2,4-DNP Test

Back 3

- Corrosive

(+) test indicates aldehydes and ketones

Solution will contain precipitate when reacted with.

False (+) - Acetone washed glass

False (-) - Aromatic/hindered ketones

Front 4

FeCL3 Test

Back 4

(+) test indicates phenol.

The solution goes from yellow to some other color.

False (-) - Sterically hindered phenols

Front 5

Ignition Test

Back 5

(+) test indicates aromatic ring (ie benzene)

Sooty/smoky flame will indicate a positive test.

False (+) - Alkyl Halides

False (-) - Aromatics with many oxygens

Front 6

Briefly explain how one can monitor the progress of a reaction by TLC.

Back 6

The reactants, reactant mixture and product are placed on the TLC sheet.

After some time has passed, the dots will have moved and aligned.

The reaction is complete when the reaction mixture has only one dot and is aligned with the product.

Front 7

What solvent will be used in the Diels-Alder reaction experiment, and what safety hazard does it present?

Back 7

Toluene - it is very flammable

Front 8

Why do cyclic dienes typically undergo Diels-Alder reactions more quickly?

Back 8

They are permentally fixed in a cis configuration.

Front 9

How will the product from today's experiment be isolated?

Back 9

By filtration

Front 10

Why is it not a good idea to clamp both the round-bottom flask and the condenser in the Diels-Alder experiment?

Back 10

It will allow air to leak into the funnel.

Front 11

Briefly explain what is meant by "heating at reflux"

Back 11

Boiling a liquid and attaching a means to recollect the evaporate so that it is constantly vaporizing and boiling.

Front 12

Why is using a cracked filter flask more dangerous than using a cracked Erlenmeyer flask?

Back 12

The fliter flask is under extreme pressure due to the vaccuum.

Front 13

Why is it necessary to remove the stopper from the seperatory funnel before draining it?

Back 13

The stopper inhibits air flow and will not allow the stopcock to release the liquid.

Front 14

Briefly explain why water was sufficient to pull the copper chloride away from the benzil, but 1M NaOH was required to seperate the p-ter-butylphenol from the benzil

Back 14

Water is a great way to pull ionic bonds apart due to its polarity, but NaOH is more basic than water and pulled the acidic H+ from the alcohol group.

Front 15

Why do cyclic dienes act faster than trans dienes?

Back 15

Cyclic are always held in cis, making them more reactive.

Front 16

What is the purpose of the watercool condenser

Back 16

Acts as an aircoil

Front 17

About how long did the Antrocene/maleic anhydrous heat at reflux?

Back 17

About one hour.

Front 18

Extraction of benzoic acid from mixed solution of benzophenone and benzoic acid

Back 18

What is happening in this reaction?

Front 19

Based on your data, which compound (napthalene, BHT or sodium benzoiate) is the most polar?

Which is the least polar?

Back 19

Sodium Benzoate is the most polar because it fully dissolved in water, a polar sovlent. Also it has a slight solutibity in Diethyl ether, which has some polarity.

Napthalene is the least polar. It was not soluble in H2O, but it was soluble in Petroleum Ether and Diethyl Ether.

Front 20

Based on the structures of the compounds, which compound (napthalene, BHT or sodium benzoate) is the most polar?

Which is the least polar?

Back 20

Sodium Bensoate is the most polar because of the depronated carboxylic acids and the Na+ ions.

napthalene is the least polar because it has no Oxygens or Nitrogens, or any type of dipole. It is strictly a hydrocarbon cyclic.

Front 21

London Dispersion

Dipole-Dipole

Back 21

List all of the intermolecular forces present in pure solutions of each compound.

Front 22

London Dispersion

Back 22

List all of the intermolecular forces present in pure solutions of each compound.

Front 23

London Dispersion

Dipole - Dipole

Hydrogen Bonding

Back 23

List all of the intermolecular forces present in pure solutions of each compound.

Front 24

Which compound (dimethyl ether, propane or ethanol) would have the highest boiling point?

The lowest?

Back 24

Ethanol

Propane

Front 25

Which compound (dimethyl ether, propane or ethanol) would be the most soluble in water?

The least?

Back 25

Ethanol

Propane

Front 26

What is one good way (in terms of technique) to try to dissolve a solid in a small amount of solvent in a test tube?

Back 26

Put a cork stopper on the test tube and shake it up

Front 27

Predict the best solvent:

Napthalene (nonpolar) should be most soluble in

Back 27

Petroleum Ether

Front 28

Predict the best solvent:

BHT (polar aprotic) should be most soluble in..

Back 28

Diethyl ether

Front 29

Predict the best solvent:

Sodium benzoate should be most soluble in...

Back 29

Water

Front 30

If a mixture of ether and water is placed in a seperatory funnel, which layer would be on the bottom?

Back 30

Water

Front 31

Extraction is a seperation technique. On the basis of what physical property are seperations achieved?

(In other words, differences in what property are used to separate mixtures of compounds when doing an extraction?)

Back 31

Solubility.

Front 32

In today's experiment, a mixture contianing the three compounds, benzyl, p-tert-butylphenol and copper (II) chloride, will be added to a mixture of ether and water.

Which layer (water) will each compound end up in?

Back 32

Cu (II) Chloride

Front 33

In today's experiment, a mixture containing the three compounds, benzyl, p-tert-butylphenol and copper (II) chloride, will be added to a mixture of ether and water.

Which layer (ether) will each compound end up in?

Back 33

benzyl
p-tert-buytlphenol

Front 34

What is the equation for P.C?

(water partition coefficient)

Back 34

P.C = {(Amt of compound in better solvent)/(volume of better solvent)}
_________________________
{(Total amt)-(amt in better solvent)/(volume of worse solvent)}

Front 35

After the first extraction (of water and ether) the compounds remaining in the ether layer are extracted with 1 M naOH (a strong base).

One of the structures changes and this compound is 'dragged' into the new water layer.

Draw the new structure and explain why this compound is suddenly soluble in water.

Back 35

This structure had it's H+ stripped away, forming an ionic bond with Na+ and making it soluble in water because of this ionic bond.

Front 36

What is the melting point of Octane according to ChemFinder?

Back 36

125.5 °C

Front 37

What is the melting point of isooctane according to ChemFinder?

Back 37

99.0 °C

Front 38

Why does isooctane have a lower boiling point than octane?

Back 38

As surface area increases, van der waals forces increases, thus raising the boiling point.

Front 39

When bubbles first start coming out of the boiling point microcapillary, why is the temperature of the oil not taken to be the boiling point of the liquid?

(In other words, why do you have to wait until the bubbles become a steady stream, and then stop when the oil is cooled?

Back 39

The bubbles began to form because of the huge increase in kinetic energy, but this does not determine exactly what the boiling point is.

The pressure is higher outside the tube than inside, and once the pressure equalizes and the temperature decreases, the boiling point can be determined.

Front 40

Would you expect the boiling point of 1-heptanol to be higher or lower than that of octane?

Back 40

1-heptanol will have a higher boiling point because of the alcohol group that contains hydrogen bonds, as well as dipole-dipole interactions

Front 41

What is recrystallization

Back 41

Technique which seperates based on solubility.

As temperature increases, so does solubility.

Front 42

T/F - Slowly cooling will yield more pure product.

Back 42

TRUE -

Front 43

What was dimethyl maleate acting as in the alkene isomerization lab?

MP 91-99 degrees C

Back 43

Starting material

Front 44

What was dimethyl fumerate acting as in the alkene isomerization lab?

MP 101-102 deg C

Back 44

Product

Front 45

What was morpholine acting as in the alkene isomerization lab?

Back 45

Nucleophile

Front 46

What was ZnCl2 acting as in the alkene isomerization lab?

Back 46

Lewis acid catalyst

Front 47

What was methanol acting as in the alkene isomerization lab?

Back 47

Solvent

Front 48

What was diethyl ether acting as in the alkene isomerization lab?

Back 48

Used in extractant

Front 49

Stationary Phase is also known as what?

Back 49

Absorbant Phase

Used Silica Gel (very polar) for chromatography.

Front 50

Mobile Phase is also known as what?

Back 50

The solvent.

In the chromatography lab, it was

Ethyl acetate .

Front 51

Rf equation

Back 51

Distance spot traveled
----------------------
Distance solvent traveled

Front 52

Solubility

Back 52

dissolving a substance into a liquid

Front 53

Solvent

Back 53

The liquid that does the dissolving

Front 54

Solute

Back 54

The substance being dissolved

Front 55

Which intermolecular force is the strongest?

- Ionic interactions
- Hydrogen bonds
- Dipole - dipole interactions
- London dispersion

Back 55

They are ranked according to their strength relative to london dispersion

Front 56

Distillation seperates based on....

Back 56

differences in boiling pointl.

Front 57

Simple distillation involves...

Back 57

An open tube that vaporizes the solution only once.

Front 58

Fractional distillation involves

Back 58

more surface area, which makes the solution vaporize and condense several times.

Front 59

Normal phase

Back 59

Silica gel -> very polar

seperates polar compounds

Front 60

Reverse phase

Back 60

Composed of (CH3)18

Very nonpolar

Located inside of the GC tube.

Seperates Nonpolar compounds

Front 61

As impurities increase...

Back 61

melting point decreases

Front 62

What color is benzil?

MP?

Back 62

yellow

95 deg C

Front 63

What color is p-tert-butylphenol?

MP?

Back 63

White

99.3 deg C

Front 64

What is atmospheric pressure

Back 64

The temperature at which a vapor pressure is above a liquid

Front 65

As atm decreases....

Back 65

BP decreases too

Front 66

Temperature is a measure of ______ in particles.

Back 66

Kinetic energy

Front 67

In Experiment 4: TLC what is the stationary phase on the TLC plate?

Back 67

The silica gel plate

Front 68

In Experiment 4: how will we visualize spots on the TLC plate

Back 68

Using UV light

Front 69

What will be the result of the following errors in TLC technique?

Too much sample is applied

Back 69

Larger spots than normal will appear, will not be able to calculate Rf

Front 70

What will be the result of the following errors in TLC technique?

Solvent of too high polarity

Back 70

The spots will be too close to the top.

Front 71

What will be the result of the following errors in TLC technique?

Solvent in developing jar too deep.

Back 71

The samples will mix together and skew results

Front 72

What will be the result of the following errors in TLC technique?

Forgetting to remove TLC plate when solvent reaches top of TLC plate.

Back 72

The Rf value cannot be determined

Front 73

For Experiment 4: TLC, would your Rf values have been higher or lower if you had used a more polar solvent than ethyl acetate as the developing solvent?

Back 73

The Rf values would have been lower if a more polar solvent was used because it would have moved the solutions closer to one another, thus lower Rf

Front 74

For Experiment 6, Alkene Isomerization

Could a catalytic amount (less than one equivalent) of morphone be used?

Back 74

Yes it could because the end product of the reaction is dimethyl fumerate and morpholine...

This allows it to catalyze other dimethyl maleate molecules.

Front 75

How is the product from Experiment 6: Alkene Isomerization going to be seperated from the reaction mixture?

Back 75

It's going to be put into a seperatory funnel that contains water and ether.

Front 76

What physical property will be used to distinguish dimethyl fumerate from dimethyl maleate?

Back 76

The melting point will increase.

Front 77

RWhat effect is recrystallization expected to have on the melting point of your product?

Back 77

The melting point should increase because crystallization favors creation of the sought after molecule and eliminates impurities...which lower the melting point.

Front 78

Why does the addition of the 10% H2SO4 result in the formation of a precipitate?

Back 78

It pulls off the Na+ ion and adds an H+. This changes the composition of the solution and forms precipitate because it's a neutral compound.

Front 79

Recrystallizatino seperates compounds based on what physical characteristic?

Back 79

Solubility

Front 80

When doing a recrystallization, what is the purpose of cooling the crystallizing solution?

Back 80

To "crash out" product

Front 81

When dissolving the crude sample in hot solvent, why is it important to not use too much solvent?

Back 81

The solvent may deprotonate the molecule that we are trying to isolate.

Front 82

After dissolving the crude sample in hot solvent, why is it better to let the solution cool slowly rather than quickly?

Back 82

This yields a purer product, quickly cooling will lead to impurities.

Front 83

When "washing" the purified product (which has been collected in the filter) why should cold water be used instead of warm water?

Back 83

The cold water will not dissolve the product, leaving us with a full collection of the product.

Front 84

Which compound (n-octane or isooctante) had the shorter retention time?

Back 84

Isooctane had the shoerter retention time beasue it was less nonpoalr than n-octane, which allowed it to move quicker through the Gas Chromotagraphy chamber.

Front 85

What is a way to determine if isomerization was complete?

Back 85

Detemine how close the experimental melting point is from the theorhetical melting point.

Front 86

Why is fractiona distillation more effective than simple sitillation for seperating liquids?

Back 86

Fractional requires that the liquids condensce multiple times, ensuring thatt the liquid is highly seperated

Front 87

Distillation seperates compounds based on what physical property

Back 87

Boiling point

Front 88

What is one advantage of fractional distillation relative to simple?

Back 88

It ensures that the liquid is more seperated than simple.

Front 89

What is one disadvantage of fractional distillation relative to simple?

Back 89

It takes much longer.

Front 90

What will be the mobile phase (gas carrier) in the gas chromatography experiment?

Back 90

SiCH2(CH3)18

Front 91

The gas chromatograph we will use today has a nonpolar column.

Which compound will flow through the column at a faster rate?

Back 91

Isooctane

Front 92

What information is gained from measuring the relative areas of peaks in a gas chromatogram?

Back 92

The % composition

Front 93

What does the number of peaks in a gas chromatogram tell you about the composition of the sample?

Back 93

The number of peaks equals the number of compounds in the sample.

Front 94

Explain why impurities lower the melting point.

Back 94

impurities disrupt the bonds of the substance we're testing.

Front 95

During this experiment you will be monitoring the temperature of the silicone oil bath.

When will the temperature of this bath equal the boiling point of your unknown?

Back 95

When the bubbles stop coming out of the microtube.

Front 96

If a storm moves in and the atmospheric pressure drops, will the observed boiling points of the unknowns increse, decrease or stay the same?

Back 96

The boiling points will decrease.

Front 97

Dimethyl maleate

Starting material

Back 97

What is this molecule's name?

What is it's purpose?

Front 98

Dimethyl fumerate

Product

Back 98

What is this molecule's name?

What is it's purpose?

Front 99

Morpholine

Nucleophile

Back 99

What is this molecule's name?

What is it's purpose?

Front 100

ZnCl2

Lewis Acid

Back 100

What is this molecule's name?

What is it's purpose?

Front 101

Methanol

Reaction Solvent

Back 101

What is this molecule's name?

What is it's purpose?

Front 102

Diethyl ether

Used in extractant

Back 102

What is this molecule's name?

What is it's purpose?