chemistry holy fuck ahhhhh

which intermediate is formed in the bromination of stillbene

cyclic bromonium ion

what is chloroform used for during caffeine extraction

as a solvent (more soluble than water)

a broad melting point range indicates

impurities are present

what is the main reason a student might obtain too low of a percent yield in a recrystalization experiment

used a solvent with high solubility at low temperatures OR heated the solution too much

In IR spectroscopy, how can you determine if oxidation from alcohol to ketone is complete

disappearance of OH and appearance of c=o stretch

In a distillation set up, which direction should water enter from

the bottom

when should one use fractional distillation over simple

mixtures with close boiling points

what indicates a high purity based on melting point

narrow range 1-2 and close to the literature values. Lower melting point and larger range indicate low purity

what is the purpose of sodium hydrosulfite in luminol synthesis

to turn the nitrile group into an amine

which component vaporizes first in distillation

the more volatile one

when should one use simple distillation

mixtures with boiling point difference greater than 35

where does a distilling column go in the apparatus

above RB flask below distill head

Will nonpolar samples be found at the top or bottom of silica plate in TLC chromatography

nonpolar will be at the top. Silica gel is polar so it binds to polar compounds more strongly, making it harder for them to move up

Omar added 5g of compound A to his mixture and recrystalized 4.5g. What is his % recovery

90%

compound A’s mw is 125 g/mol. Calculate the number of mols used in one gram when used as a solid

1 gram/125 g/mol

compound A’s mw is 125 g/mol, it has a density of 1. Calculate the number of mols used in 0.5 mL assuming the concentration is 100%

0.5 mL * 1cm3/1ml * 1 mol/125 g/mol

compound A’s mw is 125 g/mol. Calculate the number of moles used in 0.5 mL of 45% solution

(0.45 × 0.5 ml)/125

what makes an ideal solvent

dissolve solid completely when hot, but not at room temp. Should not otherwise chemically interact with rxn

what is the role of the fractionating column in fractional distillation

provide increased surface area due to beads/steel wool/etc filling it, which allows many distillation cycles to commence

which kind of distillation gives an S curve appearnace on graph

fractional

when should the separatory funnel be vented

after shaking and after inverting

why must capillary tube be sealed before using meltemp

compound would just evaporate (sublimate) away

what is the role of ethanol in pigment extraction

removes excess H2O

what is the purpose of ethyl acetate in pigment extraction

dissolve both pigmentswhat

what is the purpose of sodium sulfate in pigment extraction

remove excess H2O

what could cause you to mess up TLC

spot needs to be smaller, level of solvent in developing chamber, spot shouldnt be concentrated, too close sports, too close to the edge

what does the color change in the condensor mean in bromination of stillbene

Bromine has been generated

why does the NO2 add at the meta position duirng nitration

cooh is an electron withdrawling group

what is the purpose of the ice-salt bath in nitration

to keep the temperature low (the salt allows the temperature to go lower than 0 like the ice alone would) and to prevent the decomposition of the nitronium ion

what does sulfuric acid do in the nitration reaction

helps generate the nitronium ion (the electrophile)

what would happen if you didnt keep the reaction mixture cold during the addition of sulfuric acid to methyl benzoate

over-nitration or formation of byproducts

what does the characteristic blue glow indicate in the final chemiluminescent reaction

that the excited state of the molecule is returning to ground state

why does phosphoric acid or sulfuric acid speed up the aspirin synthesis reaction

it protonates the carbonyl oxygen of acetic anhydride, making the carbonyl carbon more electrophilic

what would happen if water were added at the beginning of the reaction instead of after heating

the reaction would not proceed efficiently as water would hydrolyze acetic anhydride

what is the electrophile in the bromination of stilbene reaction

Br2

what is the purpose of sodium bisulfite (NaHSO3) in the camphor synthesis

neutralizes excess hypochlorite (HOCl) and stops oxidization

In the camphor reacittion, what does a positive KI-starch paper test indicate

excess hypochlorite is present in the reaction mixture