uzyere
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Hi there does anyone know the questions for the 2014 OCR F321 Paper. The unofficial mark scheme is listed below.
1)a) period: 5 Block: P [1 mark]
1)b)i) isotope: Atoms of the same element (1) that have the same number of protons yet a different number of neutrons/ a different atomic mass number (1) [2 marks]
1)b)ii) The have the same outer shell electron configuration/are in the same block and thus have similar reactions [1 mark]
1)b)iii) protons: 51 Neutrons: 70 electrons: 51 [1 mark]
1)c)i) the (weighted) average/mean mass (1) of the naturally occurring isotopes/atoms of an element, relative to the mass of carbon 12 (1) which has a mass of 12 (1) [3 marks]
1)c)ii) 123 [1 mark]
1)d)i) shape: pyramidal (1)
The molecule has 3 bonded pairs and one lone pair, lone pairs have a greater repulsive effect than bonded pairs (1) [2 marks]
1)d)ii) chlorine is more electronegative than the other element present (1) pyramidal is an unsymmetrical/asyemtrical shape and thus the dipoles do not cancel out (1) [2 marks]
total for question 1: [13 marks]

2)a) method: work out the ratio by dividing the composition by mass as a percentage by the Mr of that element (1)
Then you divide each of the numbers calculated by the smallest value calculated to find a whole number ratio
Answer: CH4N2O (1) [2 marks]
2)b) Ions present: NH4+ AND NO3- [2 marks]
2)c) acid formulae: H3PO4 [1 mark] (you will not get a mark if you wrote out its name)
2)d) base name: calcium oxide/calcium hydroxide/ calcium carbonate [1 mark] (you will not get a mark if you wrote out its formulae)
total for Question 2: [6 marks]

3)a) Oxidation as electrons are lost/the oxidation number increases [1 mark]
3)b) using the volume equation with the right numbers: v=n x 24 (1)
answer: 2.88dm^3 (1) [2 marks]
3)c) using the mass equation with the correct numbers: m=Mr x n (1)
Answer: 10.7g (1) [2 marks]
3)d) using the concentration and volume equation for volume: v = (n x 1000)/ c (1)
Answer: 200cm^3 (1) [2 marks]
Total for question 3: [7 marks]

4)a)i) correct drawing with one additional H2O molecule present (they were specific with one so if you added more or didn’t add one I think you will loose a mark) Correct dipoles (delta + for hydrogen and delta – for oxygen) 2 lone pairs present on each oxygen atom, labelled hydrogen bond between the lone pair on an oxygen atom and a hydrogen atom. [2 marks]
4)a)ii) 1. Unexpectedly high melting point (1) (NOT BOILING POINT) as ice contains many hydrogen bonds due to the two lone pairs on the oxygen and the two hydrogen atoms present in each molecule, thus more energy is required to break them (1) [2 marks]
2. the solid ice is less dense than the liquid water (1) as the hydrogen bonds cause the molecules to be spread apart/open lattice structure (1) [2 marks]
4)b) two oxygen’s covalently bonded to an carbon atom, with two bonded pairs being shared, each oxygen atom has two lone pairs of electrons. [1 mark]
4)c) Giant covalent [1 mark]
4)d) Na shows metallic bonding (1), in a metallic lattice when both molten and solid delocalised electrons are free and mobile to carry an electrical charge, thus it can conduct electricity (1). Na2O is a giant ionic lattice structure (1), and due to this lattice when solid the ions cannot move freely to pass on a charge and thus it cannot conduct (1). When molten the Ions are free to move and pass on a charge and thus can conduct (1). [5 marks]
total for question 4: [13 marks]

5)a) Trend: decreases in size from lithium to fluorine (1)
Explaination: The nuclear charge/atomic number increases (1), shielding remains similar and thus nuclear attraction is greater so the force of attraction on the outermost electrons pulls them in closer to the nucleas making the atomic radius smaller (1). [3 marks]
5)b)i) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 [1 mark]
5)b)ii) cream precipitate present/ cream precipitate remains [1 mark] (they were looking for the observation after both AgNO3 and dilute ammonia had been added, they did not want the difference between the two, they just wanted the observation so I do not think OCR will allow the precipitate did not dissolve/nothing happened looking at the past papers)
5)b)iii) Ag+(aq) +Br-(aq) à AgBr(s) [1 mark]
5)c) Cl2 + 2NaOH à NaClO + NaCl + H2O (1)
Conditions: cold dilute sodium hydroxide (1) [2 marks] (clearly states in the specification and textbook cold and dilute, and in the past both have been needed for the mark)
5)c)ii) disproportionation is when a species is both oxidised and reduced (1). Cl is oxidised from 0 to +5 and reduced from 0 to -1 (1) , thus chlorine has been both oxidised and reduced (1). [3 marks]
total for question 5: [11 marks]

6)a)i) CaCO3 (s) à CaO (s) +CO2 (g) [1 mark]
6)a)ii) RACO3 [1 mark] (this answer has had many opinions, but according to my teacher they wanted you to follow the trend rather than follow the textbook and put the group two carbonate that when following the trend would be the hardest to thermally decompose)
6)b) working out the moles of the original salt to be 0.02 (1)
Working out the moles of the removed water to be 0.08 (1)
SrCl2.2H2O (1) [3 marks]
6)c)i) reaction 1: Ba + 2H2O à Ba(OH)2 +H2
Reaction 2: Ba3N2 +6H20 à 3Ba(OH)2 +2NH3
(one mark for reaction one correct, one mark for NH3 produced, one mark for correct reaction 2)
(these equations usually have to be balanced to get the marks) [3 marks]
6)c)ii) Giant Ionic With Ionic Bonding [1 mark]
6)c)iii) a Ba2+ ion with either 8 or 0 electrons in its outer shell. Two covalently bonded oxygen atoms in brackets with a 2- charge [1 mark]
total for question 6: [10 marks]
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chickensthatfly
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here, i've managed to find the link with the full paper. the questions should be there, just click on the site. hope this helps

https://www.omacademy.org/ocr-2014-p...hemistry-f321/
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MaimunahXD
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Thank you.


Maimunah
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hamzahfaqir786
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