Exact Markscheme Paper 2 Answers

Question 1

When do you use long drying agent method , and when do you use filtration reduced pressure, recrystallisation, filter again

Answer 1

Organic liquid, and aqueous layer use LONG method

Recrystallisation only for SOLIDS

Question 2

How to do recrystallisation exact

Answer 2

1) dissolve solid in minimum amount of hot solvent
2) let it cool
3) filter by reduced pressure
4) THEN WASH WIRH COLD WATER/ SOLVENT , and let it dry

Question 3

How to do melting point determination EXACT
To compare purity

Answer 3

1) obtain melting point
2) compare to known values
3) pure sample will have a SHARP melting range close to data book value

Question 4

How to check purity using spectroscopy or Tlc

Answer 4

Run a spectrum Ir or Nmr
- compar to database
- pure sample will have exact spectra of peaks and no others

TLc
- run tlc
- compare fr va,he to data
- if pure has same / similar rf !

Question 5

How ti describe reactivity if ohenol etc

Answer 5

Partially delocalised / electron withdrawing only

Attracts electrophiles more, polarises more, MORE SUSCEPTIBLE to electrophikic attack ONLY

Question 6

Why can amine react with acid

Answer 6

Musr say LONE PAIR on nitrogen can accept a H+
By donating an electron pair to H+

Question 7

Why can somehting be biodgredgable

Answer 7

Because easilly HYDROLYSED , ester link / polyester

Remember bidogdregarable just means degrades with bio so water. Not PHOTODEGRADAEBLE

Question 8

How to say more supple as a result of more oH

Answer 8

Must say forms MORE HYDROGEN BONDS WITH water must say WATEE

Question 9

Alicyclic

Answer 9

Non AROMATIC cycle

Question 10

How to say why major product forms

Answer 10

Major product forms carbocation om carbon bonded to the most alkyl groups , hence this is the one made most

Question 11

Why same structural isomers

Answer 11

Same molecular, different structural

Question 12

What are similarities and differences between kekule and delocalised overlap

Answer 12

Similarities
- both have pi bonds which are due to sideways overlap of p orbitals
-and both are overlap above and below the plane

Differences
- kekule is localised eveey alternwting carbon, 3 pi bonds
- delocalised is all p orbitals overlap with advent carbons ti form ring of system of pi bonds instead

Question 13

Phenyl amine less basic than normal why?

Answer 13

Electron partially deloclaised

So less available
To be able to donate to a proton

Question 14

Two dehydrated compounds

Answer 14

D2O is used to identity OH / NH protoms

CDCL3 is used as a solvent