Organic stuff wrong from mock

Question 1

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

Answer 1

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

Question 2

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

Answer 2

Question 3

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

Answer 3

Question 4

whats bonds can alkali hydrolysis break

Answer 4

• esters (quickly)
• amides (slowly)

Question 5

why is phenol more readily attacked by electrophiles than benzene

Answer 5

• 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

Question 6

what effects the rate of hydrolysis of haloalkanes

Answer 6

bond enthalpy

Question 7

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

Answer 7

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

Question 8

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

Answer 8

RX + OH- -> ROH + X-

Question 9

draw the machanism for chlorocyclohexane hydrolysed by aqueous sodium hydroxide

Answer 9

Question 10

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

Answer 10

reflux

Question 11

draw reflux apparatus

Answer 11

Question 12

draw distillation apparatus

Answer 12

Question 13

draw filtration apparatus

Answer 13

Question 14

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

Answer 14

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

Question 15

draw the mechanism for electrophillic addition of bromine onto ethene

Answer 15

Question 16

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

Answer 16

Question 17

explain markowinikoffs rules

Answer 17

• 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

Question 18

draw the product of salicyclic acid + Na2CO3 (aq)

Answer 18

Question 19

draw the prouduct of salicyclic aid + NaOH (aq)

Answer 19

Question 20

write the equations for the complete+incomplete combustion of methanol

Answer 20

Question 21

compare intermolecular forces

compare the boiling points of alkanes and alcohols

Answer 21

• 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

Question 22

define homologous series

Answer 22

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

Question 23

whats the general formula of alcohols

Answer 23

C_nH_2n+2O

Question 24

• what happens to bond enthalpy of X-C as you go down group 7
• what does this affect

Answer 24

• C-X bond enthalpy decreases, C-F strongest, C-I weakest
• rate of hydrolysis/nucleophilic substitution

Question 25

whats affects R_f values

Answer 25

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.

Question 26

name 3 ways of disposing of non-biodegradable polymers

Answer 26

- 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

Question 27

halide test plus further test

Answer 27

- 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 NH_3, look for prcpt dislloving - add conc ammonia obs: cl- = dissolves in dilute ammonia Br- = only dissolves in conc ammonia I- = deosnt dissolve

Question 28

what order do you do test to prevent false positive

Answer 28

carbonates-\>sulfates-\>halides

Question 29

describe the test for carbonates-\>sulphates-\>halides

Answer 29

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

Question 30

test for ammonim ons

Answer 30

- add NaOH(aq) - warm - hold damp litmus paper over top of test tube obs: paper turns blue

Question 31

test for unsaturated

Answer 31

- add Br₂ obs: decolourised Br₂

Question 32

test for 1°/2° alcohols

Answer 32

- oxidise with k2cr2o7 obs: orange to green

Question 33

test for aldehydes

Answer 33

- add tollens - place in warm water bath obs: silver mirror forms

Question 34

test for carbonyls

Answer 34

- add bradys reagents - shake obs: bright orange precipitate

Question 35

test for phenol

Answer 35

1) -add NaOH obs: fizzes, colourless solution of sodium salt would form 2) -add Na₂CO_3(s) obs: nothing happens

Question 36

test for carboxylic acids

Answer 36

-add Na₂CO_{3 Obs:} solution fizzes, CO₂ released, bubble through lime water

Question 37

atom economy formula

Answer 37

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

Question 38

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

Answer 38

Question 39

How does GC-MS work

Answer 39

- 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

Question 40

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

Answer 40

area of peak/total area of all peaks

Question 41

whats the difference between gas chromatography with liquid and solid coatings

Answer 41

- 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.**

Question 42

what 3 factors effect retention times

Answer 42

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

Question 43

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

Answer 43

-calculate the concentration of a particular substance

Question 44

4 steps to mkaing calibration curve

Answer 44

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.

Question 45

how are acid anhydrides produced

Answer 45

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

Question 46

acid anhydride + alcohol -\>

Answer 46

Ester + carboxylic acid

Question 47

formation of nitronium ion, electrophile

Answer 47

HNO₃ + H₂SO₄ -\> HSO₄^- + NO₂⁺ + H₂O

Question 48

formation of HCN from NaCN and H₂SO₄

Answer 48

2NaCN + H₂SO₄ -\> 2HCN + Na₂SO₄

Question 49

what are the bond angles in a tetrahedral molecule

Answer 49

109.5°

Question 50

why is raical substitution bad at making a single substance

Answer 50

- multiple determination steps - further substitution - substitution at anywhere on the c chain

Question 51

explain ozone depletion

Answer 51

- 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

Question 52

what radicals destroy ozone other than Cl

Answer 52

NO free radical from nitrogen oxides from vehicle engines and thunderstorms

Question 53

what are the substitutes for CFC's

Answer 53

HCFC and HFC

Question 54

what are the main greenhouse gasses, why -what factors determine how much a gas contributes

Answer 54

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

Question 55

whats global warming

Answer 55

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

Question 56

how do you ensure prduction of 1° amine

Answer 56

excess ammonia avoids further substitution to 2°/3°