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Chemistry > Organic stuff wrong from mock > Flashcards

Organic stuff wrong from mock Flashcards

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1
Q

name 2 electron donating and 1 electron withdrawing groups + what they do

A

EDG: OH, NH2. Directs electrophilic substitution towards 2-,4- and 6- positions. EWG: NO2. Directs electrophilic substitution towards 3- and 5- positions.

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2
Q

write a balanced equation for the oxidation of 3-methylbutan-1,2,3-triol

A
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3
Q

draw the equation for alkali hydrolysis of methanoic acid with NaOH (display formula)

A
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4
Q

whats bonds can alkali hydrolysis break

A
  • esters (quickly)
  • amides (slowly)
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5
Q

why is phenol more readily attacked by electrophiles than benzene

A
  • OH group is electron donating
  • lone pair in p-orbital of oxygen atom overlaps with delocalised ring
  • lone pair partially delocalised into π-system
  • increases electron density of benzene ring
  • allows phenol to polarise/attack NO2+ electrophile more readily than benzene
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6
Q

what effects the rate of hydrolysis of haloalkanes

A

bond enthalpy

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7
Q

whats the trend of C-X bond enthalpy as you go down group 7

A

bond enthalpy of C-X decreases as you go down the group, increasing the rate of hydrolysis

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8
Q

whats the general equation for the hydrolysis of haloalkanes with aqueous alkali

A

RX + OH- -> ROH + X-

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9
Q

draw the machanism for chlorocyclohexane hydrolysed by aqueous sodium hydroxide

A
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10
Q

what practical technique should be used for carrying out hydrolysis of a haloalkane

A

reflux

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11
Q

draw reflux apparatus

A
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12
Q

draw distillation apparatus

A
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13
Q

draw filtration apparatus

A
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14
Q

How would you use the products of a chemical test such as Bradys to identify a compound

A
  • precipitate formed from test can be used to measure melting point with melting point apparus
  • values can be compared to know data values
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15
Q

draw the mechanism for electrophillic addition of bromine onto ethene

A
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16
Q

draw 1°,2° and 3° carbocations and state their relative stabilities

A
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17
Q

explain markowinikoffs rules

A
  • if hydrogen halide adds to an unsymetrical alkene theres two posible products.
  • amount of product formed depends on how stable the carbocatios formed in the middle of the reaction
  • carbocations with more alkyle groups= more stable because they feed electrons towards the positive charge(shown by arrows on bonds)
  • more stable cations likely to form than less stable ones, first step of mechanism more likely to lead to the frmation of the most stable carbocation
  • major product = via more stable carbocation
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18
Q

draw the product of salicyclic acid + Na2CO3 (aq)

A
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19
Q

draw the prouduct of salicyclic aid + NaOH (aq)

A
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20
Q

write the equations for the complete+incomplete combustion of methanol

A
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21
Q

compare intermolecular forces

compare the boiling points of alkanes and alcohols

A
  • alcohols higher as -OH group forms H bonds with other alcohol molecules(and water), this is strongest intermolecular force so bp higher
  • alakanes only form london forces between molecules(weaker than H bonds). Longer carbon chain ->larger molecular surface area -> more surfaece area contact bewtween molecules + more elctrons -> more london forces, more energy to overcome, higher bp
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22
Q

define homologous series

A

a family of organic compounds that have the same general formula and similar chemical properties

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23
Q

whats the general formula of alcohols

A

CnH2n+2O

24
Q
  • what happens to bond enthalpy of X-C as you go down group 7
  • what does this affect
A
  • C-X bond enthalpy decreases, C-F strongest, C-I weakest
  • rate of hydrolysis/nucleophilic substitution
25
Q

whats affects Rf values

A

level of adosrbtion, a substance thats strongly adsorbed wont travel as far giving it a smaller value. chemical properties such as polarity affect how strongly adsorbed a substance is. Also depends on solid coating on the plate, solvent used, and other external factors e.g. temp.

26
Q

name 3 ways of disposing of non-biodegradable polymers

A
  • burying in landfill
  • recycling plstics, sorted into group, some melted and remoulded, other cracked into monomers used as organic feedstock
  • burning plastic waste, is recycling isnt possible, heat used to generate electricity, produces toxic gasses e.g. HCl. removed by scrubbers that neutralise
27
Q

halide test

plus further test

A
  • dissolve in distilled water
  • add dilute nitric acid (HNO3)
  • add silver nitrate(AgNO3)
  • silver halide precipitate forms
    obs: cl=white

Br= cream

I= yellow

If still indistinguishable furher ammonia test

  • add dilte NH3, look for prcpt dislloving
  • add conc ammonia
    obs: cl- = dissolves in dilute ammonia

Br- = only dissolves in conc ammonia

I- = deosnt dissolve

28
Q

what order do you do test to prevent false positive

A

carbonates->sulfates->halides

29
Q

describe the test for carbonates->sulphates->halides

A

carbonates: -add diltue strong acid(HNO3)
obs: CO2 relased, limewater
sulphates: -add barium nitrate, Ba(NO3)2(aq)
obs: white prcpt forms
halides: -add nitric acid, then silver nitrate
obs: prcpt forms, cl=white, br=cream, i=yellow

30
Q

test for ammonim ons

A
  • add NaOH(aq)
  • warm
  • hold damp litmus paper over top of test tube
    obs: paper turns blue
31
Q

test for unsaturated

A
  • add Br2
    obs: decolourised Br2
32
Q

test for 1°/2° alcohols

A
  • oxidise with k2cr2o7
    obs: orange to green
33
Q

test for aldehydes

A
  • add tollens
  • place in warm water bath
    obs: silver mirror forms
34
Q

test for carbonyls

A
  • add bradys reagents
  • shake
    obs: bright orange precipitate
35
Q

test for phenol

A

1) -add NaOH
obs: fizzes, colourless solution of sodium salt would form
2) -add Na2CO3(s)
obs: nothing happens

36
Q

test for carboxylic acids

A

-add Na2CO3

Obs: solution fizzes, CO2 released, bubble through lime water

37
Q

atom economy formula

A

(Mr of desired product/sum of Mr’s of products) X100

38
Q

draw mirror images of optical isomers of amino acid with R=CH

A
39
Q

How does GC-MS work

A
  • sample is injected and vapourised
  • stream of carrier gas carries the sample through a coiled tube coated with a viscous liquid or a solid
  • time taken for substance to pass through coiled tube and reach detector = retnetion time
40
Q

how do you work out the % in orginal mixture of a compound from a ags chromatogram

A

area of peak/total area of all peaks

41
Q

whats the difference between gas chromatography with liquid and solid coatings

A
  • in liquid the components will constantly dissolve in it, evaporate into gas, and then redissolve as they travel through the tube. Solubility determines retention time. High solubility = more time dissolved, so longer to travel through detector than one with lower solubility
  • in solid, strength of adsorbtion to solid determines retention times.
42
Q

what 3 factors effect retention times

A

1) solubility/adsorbtion, determines how long each component of the mixture spends in the stationary phase
2) boiling point, substance with high boiling points will spend more time condensed as a liquid in the tube than a gas. larger retention time
3) temperature og GC, high temp = more time evaporated as gas so will move along faster, shortens retention time

43
Q

what does creating an external calibration curve from GC allow you to do

A

-calculate the concentration of a particular substance

44
Q

4 steps to mkaing calibration curve

A

1) create series of standard solutions of different concentrations of analyte
2) one by one, inject all standard solutions recording results
3) calculate area under the peak that corresponds to the analyte
4) plot these area value on a graph of area against concentration, draw line of best fit

its a good idea to run a blank when making calibration curve. subtracting chromatogram of blank from each of chromatograms you can find correct peak value.

45
Q

how are acid anhydrides produced

A

2 identical carboxylic acids molecules join together via and oxygen with the carbonyl groups on either sides.

46
Q

acid anhydride + alcohol ->

A

Ester + carboxylic acid

47
Q

formation of nitronium ion, electrophile

A

HNO3 + H2SO4 -> HSO4- + NO2+ + H2O

48
Q

formation of HCN from NaCN and H2SO4

A

2NaCN + H2SO4 -> 2HCN + Na2SO4

49
Q

what are the bond angles in a tetrahedral molecule

A

109.5°

50
Q

why is raical substitution bad at making a single substance

A
  • multiple determination steps
  • further substitution
  • substitution at anywhere on the c chain
51
Q

explain ozone depletion

A
  • ozone levels stable until recently due to dynamic equillibrium in stratosphere
  • CFC’s lead to ozone depletion
  • stable(high bond enthalpy) so not broken down in atmosphere
  • broken down by UV radiation in stratosphere
52
Q

what radicals destroy ozone other than Cl

A

NO free radical

from nitrogen oxides from vehicle engines and thunderstorms

53
Q

what are the substitutes for CFC’s

A

HCFC and HFC

54
Q

what are the main greenhouse gasses,

why

-what factors determine how much a gas contributes

A

water vapour, CO2, methane,

bonds absorb infrared->vibrate->kinetic energy->raising overall temp

  • how much IR absorbed per molecule,
  • how much gas in atmosphere
  • how long gas stays in atmosphere
55
Q

whats global warming

A

rise is greenhouse gas concentrations, enhancing greenhouse gas effect. more heat trapped heating earth

56
Q

how do you ensure prduction of 1° amine

A

excess ammonia

avoids further substitution to 2°/3°

Chemistry (14 decks)

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