Farr High School. NATIONAL 5 CHEMISTRY Unit 1 Chemical Changes and Structure. Exam Questions (UPDATED MAY 2017)

Transcription

1 Farr High School NATIONAL 5 CHEMISTRY Unit 1 Chemical Changes and Structure Exam Questions (UPDATED MAY 2017)

2 Chemical Changes and Structure PPQ answers Rates of Reaction = 2.75 accept scales correct and both labels and units correct plotting of points and joining of points Max of 1 mark if bar graph/spike graph (labels, units and scale) or if both scales taken from table Allow ½ box tolerance on plotting of points for each Allow 1 plotting error Axes can be reversed 3. Answer Units not required Units not required 5. D 6. C 7. A 8. D 9. (a) scales correct and both labels and units correct plotting of points and joining of points Max of 1 mark if bar graph/spike graph (labels, units and scale) or if both scales taken from table Allow ½ box tolerance on plotting of points for each Allow 1 plotting error Axes can be reversed Must check reading from graph 0.5 tolerance No graph drawn (c) ( )/10 = (a) points and line correct 1/ = 80secs 11. A 12. This is an open ended question 1 mark: The student has demonstrated a limited understanding of the chemistry involved. The candidate has made some statement(s) which is/are relevant to the situation, showing that at least a little of the chemistry within the problem is understood. 2 marks: The student has demonstrated a reasonable understanding of the chemistry involved. The student makes some statement(s) which is/are relevant to the situation, showing that the problem is understood. 3 marks: The maximum available mark would be awarded to a student who has demonstrated a good understanding of the chemistry involved. The student shows a good comprehension of the chemistry of the situation and has provided a logically correct answer to the question posed. This type of response might include a statement of the principles involved, a relationship or an equation, and the application of these to respond to the problem. This does not mean the answer has to be what might be termed an excellent answer or a complete one. (3)

3 cm 3 s -1 or 0 8 cm 3 /s with no working (3) 14. C For partial marking Maximum 2 marks for calculation. Final mark is awarded for the correct unit or or 24/ (this answer without working 2 marks) The mark for the correct unit, cm 3 s -1 or cm 3 /s or cubic centimetres per second or cm 3 per second, is independent of the other marks. 15. (a) exothermic (i) 0.85 with no working (2) or OR 17/ (ii) Any value greater than 50 and less than or equal to 60. (iii) Faster / quicker / increase /speed up

4 Atomic Structure and Bonding Related to Properties of Materials 1. (a) (2) 2. (a) 3. RuCI 2 Ru 2+ (Cl - ) 2 CI 2 Ru Ru 1 CI 2 If ionic formula used it must be fully correct 4. 2

5 5. 6. sodium phosphate 7. (a) 8. (a) (i) (ii) (a) 11.

6 (a) (c) 14. (a) D 18. (a) Repulsion/repelled by nucleus/positive nucleus/protons/positive protons/positive particles in nucleus or in atom of gold/like charges in nucleus, atom or gold (i) protons 79, electrons 79, neutrons 118 (All for 1 mark) (ii) Same atomic number / protons AND different mass number / mass / number of neutrons Atoms of the same element with different mass number / mass /number of neutrons Candidate must specify either same atomic number or number of protons/positive charges or atoms of the same element AND different mass number/mass/number of neutrons 19. (a) (From top to bottom) Covalent network ionic lattice metallic lattice (discrete) covalent molecular) (All 4 correct = 2 marks, 2 or 3 correct = 1 mark, 1 or 0 correct = 0 marks) delocalised/able or free to move or correct description (mention of ions = incorrect)

7 20. A 21. B 22. D 23. C 24. D 25. C (a) 2, 8, 6 or a correct target diagram Mg(g) Mg + (g) + e - Mg Mg + + e Mg(g) Mg + + e - Mg Mg + (g) + e Or Mg(g) - e - Mg + (g) etc. (c) Decreases or As you go from lithium to potassium (alkali metals) it (ionisation energy) decreases. or As you go from fluorine to bromine (halogens) it (ionisation energy) decreases. or as the atomic number in the group increases it decreases 28. (a) carbon monoxide or CO/2CO covalent

8 29. D 30. D 31. B 32. B 33. C 34. (a) (i) (ii) 14.5 (c) pyramidal OR trigonal pyramidal 35. (a) unreactive OR does not react with water/air/alkalis/(almost all) acids OR can be beaten into shape OR found uncombined 118 Au (c) (i) CO + O 2 CO 2 OR CO + O 2 CO 2 (ii) catalyst OR catalysis OR speeds up the reaction OR allows less energy/heat to be used for the reaction OR lowers activation energy

9 Formulae and Reaction Quantities (a) (2) 3. (2)

10 4. (a) 5. (a) 6. 7.

11 8. (a) 25g (2) 11. A 12. C 13. (a) Potassium is an essential element or humans/human body cannot store it/have no mechanism for storing it or 0.02 (moles) with no working (2) 0.86 / 39 = or 0.02 (moles) (c) lilac/purple (d) K + NO 3 - (both charges must be shown) (accept the use of brackets that do not negate)

12 14. C 15. B 16. A 17. (a) 3 (Fe 3+ ) 2 (O 2- ) 3 OR Fe 3+ 2O 2-3 OR (Fe 3+ ) 2 O 2-3 OR Fe 3+ 2(O 2- ) 3 OR Fe 2 3+ O 3 2 (c) exothermic or exothermal 18. (a) Boil it or boil off the water or heat it or leave it for some time/overnight/next lesson or leave it on the window ledge or use Bunsen (burner) or appropriate diagram 0 2 with no working (2) Partial marking 19. A 3 19/159 5 = /0 1 = 0 2 (this step on its own 2 marks) or (3 19 in 100 cm 3 ) 31 9 in 1000 cm 3 or 1 litre 31 9/159 5 = 0 2 (this step on its own 2 marks) with no working 2 marks 0.01 moles gives moles x 24 = 0.36 (this step on its own 2 marks) 21. H 3 PO 4 + 3NH 4 OH (NH 4 ) 3 PO 4 + 3H 2 O FM = /232 5 x 100 = 86 2% or 86% 86 2% or 86% on its own 2 marks Use of atomic numbers max 1 mark, must have working to gain the mark, 83 3% Metal other than Hg max 1 mark

13 with no working (3) GFM = 160g 112/160 x 100 = or or 17.3 with no working 3 marks GFM /162 x 100 (concept mark) 1 mark for correct arithmetic

14 Acids and Bases (a) Spectator ions/spectate 3. a higher 4. Copper carbonate CuCO 3 5. Neutralisation 6. (a) Red/pink/orange/yellow 7. D 8. A 9. A 10. A 11. (a) Paper X Blue; Paper Y Red Both correct 12. (a) 16 Ammonium chloride (correct formula accepted) 0.08 with no working = 3 marks 0 1 x = /2 = /0 01 = on its own 3 marks or 0 1 x 16 = C 2 x = C 2 x 10 C 2 = 0 08 or any alternative correct method

15 13. C 14. A 15. D 16. A 17. B 18. B 19. (a) 1 st = hydrogen, 2 nd = hydroxide (both required for 1 mark) It/calcium oxide is a base or forms an alkaline solution (alkali) when dissolved in water. For the mention of alkali the candidate must explicitly state the calcium oxide is in solution/dissolved in water Mention of it neutralising sulfur dioxide/it neutralises it/or a neutralisation reaction takes place. 20. (a) /3 2 x 10-3 with no working or correctly rounded answer (3) Partial marking x = mol I mol of Vit C (this step on its own gets 2 marks) /0 025 = /3 2 x10-3 (this step on its own gets 3 marks) or x 16 = 0 08 mol I mol of Vit C (this step on its own gets 2 marks) 0 08/25 = /3 2 x 10-3 (this step on its own gets 3 marks) or C 1 x 25 = x C 1 x 25 = 0 08 (this step on its own gets 2 marks) C 1 = /3 2 x 10-3 (this step on its own gets 3 marks) or C 1 x = x C 1 x = (this step on its own gets 2 marks) C 1 = /3 2 x 10-3 (this step on its own gets 3 marks) OR ANY OTHER ACCEPTABLE METHOD

16 21. C 22. (a) Weak acid, strong base/alkali (both required for 1 mark) 15.0