F321 UNOFFICIAL mark scheme May 2014 with equivalent marks

How so ??????

June 2009 question 2C identical question; i've posted the answer above this post

So if u didn't mention metallic bonding would I get all marks??

What are the marks then?

How so ??????

Did the question explicitly mention structure? Because I mainly talked about conductivity but my answers are normally quite wordy so i may have referenced it somewhere.

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(c) Compare and explain the electrical conductivities of sodium and sodium oxide in the solid and
liquid states.

http://www.ocr.org.uk/Images/61530-question-paper-unit-f321-01-atoms-bonds-and-groups.pdf

Click on the link above to see the question in June 2009 paper.

The question wanted to know that
Sodium Oxide solid- Doesn't conduct elec(1) because ions are fixed(1)
Sodium Oxide liquid- Does conduct elec(1) because ions are mobile(1)
Sodium- Does conduct elec because delocalised elec are free to move and hence they can conduct elec.

June 2009 question 2
(c) Compare and explain the electrical conductivities of sodium and sodium oxide in the solid and
liquid states.
sodium is a (good) conductor because it has mobile
electrons OR delocalised electrons OR electrons can move
sodium oxide does not conduct as a solid
sodium oxide conducts when it is a liquid
ions cannot move in a solid
ions can move
OR
are mobile when liquid




I wrote this exact model answers and I think it should be 5 marks if it's the identical question and they told us specifically about conductivity; fair enough if they said comment on the structure but I just remembered this question from a past paper and wrote out the mark scheme answer

You seem familiar with marks schemes. Can you help me out please-
For the question on the last page with equations-

reaction 1: Ba + 2H2O à Ba(OH)2 +H2
Reaction 2: Ba3N2 +6H20 à 3Ba(OH)2 +2NH3

Will I gain no marks if I wrote the equations other way around accidently? i.e.
reaction 1:Ba3N2 +6H20 à 3Ba(OH)2 +2NH3
Reaction 2: Ba + 2H2O à Ba(OH)2 +H2
Even though the 2 reactions have completely different balancing and one has Ba3N2, so you can clearly tell it was an accident even though I got the equations right! Examines are usually harsh with chem. just wondering whether 3 marks go down the drain

Maybe 1/3 , I don't know about that because that's solely down to the marker / team leader, scientifically what you stated is incorrect but there are marks for BOD (benefit of the doubt) and they can be applied considering slip-ups are common due to lack of time/pressure of the exams but they're not explicitly used or it would just mean they're marking wrong answers right if you know what I mean.

Hmm looks like the lack of time costed me 3 marks.
Thanks anyway

In question 3 I used 0.8 instead of 0.08 the entire way through, will I lose all 6 marks?

You will probably lose one of the marks on the first part, then gain the marks for error carried forward (providing everything else is correct)

For 6 (b) (the water of crystallisation one) can anyone explain to me why it was •2H2O?

I got the moles correct but used the calculator value when I put it in the calculator; I got •3H2O. I was probably being massively thick and panicking because time was running out though I did 0.08 ÷ 0.0245 and got around about 3 and didnt have time to do much else to it so just left it as that. Was I missing out some information from the question that I needed to use to get to 2? Thanks

You did the same thing I did, the 0.08 is correct but you worked out the moles of substance left after water was removed, you were supposed to just use the 5.*** number they gave you NOT minus the g of water. This would have given you something along the lines of 0.08/0.02 ish and therefore 4. You then minus this from the original 6 and get 2. Too bad I didn't realise that in the exam either aha