OCR Chemistry A January 2011 Mark Scheme [F321]

Mark Scheme for January 2011, chemistry specification a for ocr.  Especially useful if resiting. Question paper:http://getrevising.co.uk/resources/ocr_chemistry_a_january_2011_question_paper_f321

 "If we are gonna perform Inception then we need imagination."  Do you love watching films? Check out this site, http://www.lovefilm.com/mbfcar4gq/visitor/sign_up_1.html.

HideShow resource information
  • Created by: MatthewJG
  • Created on: 22-05-11 12:06

Pages in this set

Page 1

Preview of page 1
GCE

Chemistry A
Advanced Subsidiary GCE
Unit F321: Atoms, Bonds and Groups




Mark Scheme for January 2011




Oxford Cambridge and RSA Examinations

Page 2

Preview of page 2
OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of
qualifications to meet the needs of pupils of all ages and abilities. OCR qualifications include
AS/A Levels, Diplomas, GCSEs, OCR Nationals, Functional Skills, Key Skills, Entry
Level qualifications, NVQs and vocational qualifications in areas…

Page 3

Preview of page 3
F321 Mark Scheme January 2011
Question Answer Mark Guidance
1 (a) Rb-87 has (two) more neutrons 1 ALLOW Different numbers of neutrons

ALLOW 2 neutrons

ALLOW Rb-85 has 48 neutrons AND Rb-87 has 50 neutrons

IGNORE correct references to protons and electrons

DO NOT ALLOW incorrect references to protons and…

Page 4

Preview of page 4
F321 Mark Scheme January 2011
Question Answer Mark Guidance
1 (d) Spherical OR sphere 1 DO NOT ALLOW `circular'
IGNORE unlabelled 2-D diagrams
(e) (i) Sr+(g) Sr2+(g) + e­ 1 ALLOW e for electrons
ALLOW Sr+(g) ­ e­ Sr2+(g)
DO NOT ALLOW Sr+(g) + e­ Sr2+(g) + 2e­
IGNORE state…

Page 5

Preview of page 5
F321 Mark Scheme January 2011
Question Answer Mark Guidance
1 (e) (iii) 2nd IE of Rb involves removing electron from shell 2 IGNORE new shell
closer to nucleus
ALLOW There is one shell fewer in Rb(+) (than Sr+)
ALLOW Rb(+) has a smaller radius (than Sr+)
ALLOW Rb(+) loses an…

Page 6

Preview of page 6
F321 Mark Scheme January 2011
Question Answer Mark Guidance
2 (a) (i) mol of H x A = 25.00 × 0.0500 = 1.25 × 10­3 OR 0.00125 1 ALLOW 0.0013 OR 1.3 × 10-3
mol
1000 ALLOW correct answer only without working

(ii) mol of NaOH = 1 ALLOW correct…

Page 7

Preview of page 7
F321 Mark Scheme January 2011
Question Answer Mark Guidance
2 (c) Cu(NO 3 ) 2 ·6H 2 O 1 ALLOW Cu(NO 3 ) 2 6H 2 O
ALLOW Cu(NO 3 ) 2 (H 2 O) 6
ALLOW Cu(NO 3 ) 2 .6H 2 O

DO NOT ALLOW CuN 2 O…

Page 8

Preview of page 8
F321 Mark Scheme January 2011
Question Answer Mark Guidance
3 (a) The ability of an atom to attract electrons 2 ALLOW `attraction of an atom for electrons'
ALLOW `pull' for `attract'
DO NOT ALLOW `element' for `atom'
in a covalent bond ALLOW `shared pair' or `bond(ing) pair' for `covalent bond'…

Page 9

Preview of page 9
F321 Mark Scheme January 2011
Question Answer Mark Guidance
3 (c) (iii) BF 3 is symmetrical 2 IGNORE `polar bonds cancel'
The dipoles cancel out IGNORE `charges cancel'

Total 11




7

Page 10

Preview of page 10
F321 Mark Scheme January 2011
Question Answer Mark Guidance
4 (a) Used to neutralise acidic soils 2 ALLOW raises the pH of the soil
IGNORE references to fertilisers

Excess will result in soils becoming too alkaline (to ALLOW pH becomes too high
sustain crop growth) IGNORE `harmful'
IGNORE `corrosive'
(b)…

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »