amino acids and polymer test ms

7/25/2019 Amino Acids and Polymer Test Ms

1/4

Amino Acid and Polymers Mark Scheme

1. (a) 2-amino(e) propanoic acid (1)

(b) (i) molecules with same structure / structural formula (1)

but with bonds (atoms or groups)arranged differently in space

(3D) (1)

(ii) Plane polarised light (1)

Rotated (equally) in opposite directions (1)

(c)

! ! "

#

#2

$(1)

allow H2NCH2COO

Penalise NH2- and OH- once per paper

but CH3 is allowed

(d)

3

3

2

2

!

!

( ! # " )!

!

!

!

"

"

!

!

!

!

"

"

#

#

#

#

#

#

( 1 )

( 1 )

Not anhydrides; not repeating units

(e)

3

! ! "

#

# ! 2 (1)

or H2NCH2COOCH3

[9


2/4

2. (a) (i) !3!%!!3&ddition or radical (QoL)

(ii) !3!(#)!(#)!3or with no brac'ets

butan(e)$23$diol or 23$butan(e)diol

# # ! ! ! ! # #

! ! 33

! l # ! ! ! ! # ! l

! ! 33

a l l o w

23$dimethylbutan(e)dioic acid

ignore $*$

condensation (QoL)

23$dimethylbutan(e)dioyl chloride

(iii) "a# or !l etc or "a2!#3Allow conc sulphuric/nitric

NOTwater nor acidified water nor weak acids

(b) +tructure

!

! "

2 !

#

"

! #

!

! # #

3 2

Allow CONH and COHN

Allow zwitterions

NOT polypeptides/repeating units

+tructure 2 either of

!

! "

2 !

#

"

! #

!

! # #

32 !

! # # !

2!

"

#

! #

!

"

3 2

o r

(c) (i) !3!2!2,r

allow Cl, I

(ii) !3!2!"

(iii) (nucleophilic) substitution or from !3!2!2,r

further substitution/reaction occurs or other products are formed

if reduction written here, no further marks

Allow reduction forms only one product

one of

(!3!2!2)2"

(!3!2!2)3"

(!3!2!2)*",r

$

Allow salts including NH!r

Allow H!r[!"


3/4

3. (a) polyamide or nylon (2*)

"allow nylon without num#ers #ut if num#ers are present they must #e

correct$

condensation

(b) " ! ! # #

- $

3 2

(c) ionic bonding in aminoethanoic acid

"can only score if includes that aminoethanoic is ionic$

stronger attractions than ydrogen bonding in hydro.yethanoic

"e%g% stronger Hydrogen #onding in aminoethanoic acid scores &$

"mention of electrostatic forces #etween molecules scores &$["

. (a) (i) " ! ! # #

! ( ! )

! #

$2

2

3 2

(1)

ignore Na'unless co(alently #onded

(ii) " ! ! " ! ! # #

#

! ( ! ) ! ( ! )3 32 2

2 (1)

must #e dipeptide, not polymer nor anhydride

allow CONH or COHN

allow zwitterion(iii) hydrogen bonding (1)

)*

Allow with dipole+dipole or ( deraals, #ut not

dipole+dipole etc alone


4/4

(b) (i) -ype of polymerisation addition(al) (1)

.epeating unit ! !

!

! !

3

3 3

m u s t s h o w l i n ' i n g b o n d s

(1)

not multiples

allow n

(ii) !3!%!!2!3(1)

!20

(iii)

( 1 )o r e t c

a l l o w

e t c

o rb u t n o t

2 2

2

2

22

2 2

2 2

[#

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