Orgo Lab Final

1 HBD and 2 HBAs

How many HBAs and HBDs are in this molecule?

D) boiling point; water solubility

As you add carbons to a chain, it would necessarily increase in __________ but decrease in _________

A) water solubility; boiling point

B) hydrogen bonds; water solubility

C) water solubility; hydrogen bonds

D) boiling point; water solubility

A) A solute becomes less soluble in the solvent

Recrystallization occurs when

A) A solute becomes less soluble in the solvent

B) A solute becomes more soluble in the solvent

C) A solute maintains its solubility

D) A solute is the solvent

B) A solution is heated to dissolve the solute and then cooled to crystallize it out

Which of the following would likely be a good method of recrystallization?

A) A solution is cooled to dissolve the solute and then heated to crystallize it out

B) A solution is heated to dissolve the solute and then cooled to crystallize it out

C) A solution is stirred vigorously

D) A solution is heated to evaporate all solvent

D) A differently polar solvent could be used to decrease the solubility of the solute

How can adding solvent be used to induce crystallization?

A) A differently polar solvent could be used to increase the solubility of the solute

B) A similarly polar solvent could be used to reduce the solubility of the solute

C) A similarly polar solvent could be used to increase the solubility of the solute

D) A differently polar solvent could be used to decrease the solubility of the solute

A) polar; nonpolar

Silica gel is _____ and therefore tends to stick to other _____ compounds

A) polar; polar

B) polar; nonpolar

C) nonpolar; polar

D) nonpolar; nonpolar

C) All compounds

Using a more polar solvent system moves _________ further up the plate

A) polar compounds

B) nonpolar compounds

C) all compounds

D) no compounds

B) 75% DCM in hexanes

The silica plate below was run with 50% DCM in hexanes. Which of the following solvent mixes would be a reasonable solvent system to try next?

A) 25% DCM in hexanes

B) 75% DCM in hexanes

C) Trick question, this run was perfect already

not that far

More polar substances will travel further or not that far on a TLC plate?

further

Nonpolar substances will travel further or not that far on a TLC plate?

left molecule is least, middle molecule is middle, and right molecule is most

Rank the following from least to most polar

bottom

If I use a very nonpolar solvent to run a TLC plate, will the spots be bunched at the bottom or bunched at the top of the plate?

top

If I use a very polar solvent to run a TLC plate, will the spots be bunched at the bottom or bunched at the top of the plate?

DCM on bottom, water on top

If I run an extraction using DCM and water, which would be on the bottom and which on the top?

a drying agent

What is MgSO₄?

DCM has a lower boiling point, so we didn’t have to use the roto vap that long

In experiment 4, we used DCM instead of ethyl acetate for an extraction; the DCM formed the organic layer, and water formed the aqueous layer. Why was it more practical for us to use DCM instead of ethyl acetate?

Because the aqueous layer typically has a very polar solvent like water, and boiling off water would take a while bc it has h bonds

In experiment 4, why was it better that we got the product in the organic layer rather than the aqueous layer?

B) bonds

infrared spectroscopy looks to classify molecules based on the absorbance of their

A) atomic nuclei

B) bonds

C) lone pairs

D) molecular orbitals

A) smaller; increase

In general, wavenumber goes up when atoms are _______ and as bonds ___________ in bond order

A) smaller; increase

B) larger; decrease

C) smaller; decrease

D) larger; increase

distance spot moved / distance solvent front moved

formula for R_f?

D) to cool the vapor down

What is the purpose of the condenser in a distillation apparatus?

A) to heat the vapor up

B) to increase the vapor pressure of the solution

C) to decrease the vapor pressure of the solution

D) to cool the vapor down

C) Molecule A

Molecule A has a boiling point of 38 degrees Celsius and molecule B has a bp of 55. Which is being isolated first out of a condensing apparatus?

C) in the middle of the intended products to ensure adequate separation

What would a good criteria be for the temperature of a fractional distillation?

A) higher than all products to ensure complete distillation
B) Lower than all products to ensure complete distillation

C) in the middle of the intended products to ensure adequate separation

Vigreux column

What is the name of the column that uses theoretical plates to help separate substances when performing a fractional distillation?

to ensure uniform heating

What is the purpose of the aluminum foil surrounding the column in fractional distillation?

It can lyse the membrane of bacterial cells.

Why is soap antibacterial in nature?

C) 50% EtOAc in hexanes

Which of the following solvents should you use to speed up your column chromatography experiment?

A) 10% EtOAc in hexanes

B) 30% EtOAc in hexanes

C) 50% EtOAc in hexanes

D) none of the above, the solvent doesn’t impact how quickly something moves through a column

acetaminophen on the right is more polar than aspirin on the left

Which of these is more polar? What are their names?

So the force of you putting the solvent on top of your sample is evenly distributed across the width of the column, and then the sample will travel in a level fashion down the column

What is the purpose of sand in a column chromatography experiment?

meta

In the nitration of methyl benzoate experiment, what position did the nitro group prefer to add?

THROUGH ALL QUIZZES / POST LABS TO OCT 29