Chemistry > AQA > A-level CHEMISTRY 7405/2 Paper 2 Organic and Physical Chemistry Mark scheme June 2020 Version: 1.0 F (All)

A-level CHEMISTRY 7405/2 Paper 2 Organic and Physical Chemistry Mark scheme June 2020 Version: 1.0 Final

Document Content and Description Below

By way of illustration, the following would apply. CH3 C C CH3 C CH3CH2 OH C C OH allowed allowed not allowed not allowed not allowed NH2 C C NH2 NH2 NH2 NO2 allowed allowed allowed allow... ed not allowed CN C C CN COOH C C COOH C COOH not allowed not allowed not allowed not allowed not allowed CHO C C CHO C CHO COCl C C COCl not allowed not allowed not allowed not allowed not allowed • Representation of CH2 by C−H2 will be penalised • Some examples are given here of structures for specific compounds that should not gain credit (but, exceptions may be made in the context of balancing equations). CH3COH for ethanal CH3CH2HO for ethanol OHCH2CH3 for ethanol C2H6O for ethanol CH2CH2 for ethene CH2.CH2 for ethene CH2:CH2 for ethene • Each of the following should gain credit as alternatives to correct representations of the structures. CH2 = CH2 for ethene, H2C=CH2 CH3CHOHCH3 for propan-2-ol, CH3CH(OH)CH3 MARK SCHEME – A-LEVEL CHEMISTRY – 7405/2 – JUNE 2020 8 • In most cases, the use of ‘sticks’ to represent C ─ H bonds in a structure should not be penalised. The exceptions to this when “sticks” will be penalised include • structures in mechanisms where the C ─ H bond is essential (eg elimination reactions in halogenoalkanes and alcohols) • when a displayed formula is required • when a skeletal structure is required or has been drawn by the candidate. 3.13 Organic names As a general principle, non-IUPAC names or incorrect spelling or incomplete names should not gain credit. Some illustrations are given here. Unnecessary but not wrong numbers will not be penalised such as the number ‘2’ in 2- methylpropane or the number ‘1’ in 2-chlorobutan-1-oic acid. but-2-ol should be butan-2-ol 2-hydroxybutane should be butan-2-ol butane-2-ol should be butan-2-ol 2-butanol should be butan-2-ol ethan-1,2-diol should be ethane-1,2-diol 2-methpropan-2-ol should be 2-methylpropan-2-ol 2-methylbutan-3-ol should be 3-methylbutan-2-ol 3-methylpentan should be 3-methylpentane 3-mythylpentane should be 3-methylpentane 3-methypentane should be 3-methylpentane propanitrile should be propanenitrile aminethane should be ethylamine (although aminoethane can gain credit) 2-methyl-3-bromobutane should be 2-bromo-3-methylbutane 3-bromo-2-methylbutane should be 2-bromo-3-methylbutane 3-methyl-2-bromobutane should be 2-bromo-3-methylbutane 2-methylbut-3-ene should be 3-methylbut-1-ene difluorodichloromethane should be dichlorodifluoromethane MARK SCHEME – A-LEVEL CHEMISTRY – 7405/2 – JUNE 2020 9 3.14 Organic reaction mechanisms Curly arrows should originate either from a lone pair of electrons or from a bond. The following representations should not gain credit and will be penalised each time within a clip. H3C Br H3C Br H3C Br . . . . OH OH .. _ _ : For example, the following would score zero marks H3C C H H Br HO When the curly arrow is showing the formation of a bond to an atom, the arrow can go directly to the relevant atom, alongside the relevant atom or more than half-way towards the relevant atom. In free-radical substitution • the absence of a radical dot should be penalised once only within a clip. • the use of half-headed arrows is not required, but the use of double-headed arrows or the incorrect use of half-headed arrows in free-radical mechanisms should be penalised once only within a clip The correct use of skeletal formulae in mecha [Show More]

Last updated: 1 year ago

Preview 1 out of 29 pages

Add to cart

Instant download

We Accept:

We Accept
document-preview

Buy this document to get the full access instantly

Instant Download Access after purchase

Add to cart

Instant download

We Accept:

We Accept

Reviews( 0 )

AQA

$8.00

Add to cart

We Accept:

We Accept

Instant download

Can't find what you want? Try our AI powered Search

OR

REQUEST DOCUMENT
56
0

Document information


Connected school, study & course


About the document


Uploaded On

Jan 18, 2022

Number of pages

29

Written in

Seller


seller-icon
renurse

Member since 3 years

30 Documents Sold


Additional information

This document has been written for:

Uploaded

Jan 18, 2022

Downloads

 0

Views

 56

Document Keyword Tags

Recommended For You

Get more on AQA »
What is Browsegrades

In Browsegrades, a student can earn by offering help to other student. Students can help other students with materials by upploading their notes and earn money.

We are here to help

We're available through e-mail, Twitter, Facebook, and live chat.
 FAQ
 Questions? Leave a message!

Follow us on
 Twitter

Copyright © Browsegrades · High quality services·