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OCR Chemistry B (Salters) Thursday 10th January Discussion

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Reply 300
Avatar for krisshP
krisshP
14
Original post by NielsBohrsDad
I wrote that the carbon and silicon atoms in the molecules make them different
i really dont think it was a remembrance question
more of a common sense and make you think hard, when its really that easy question
Because it did only mention the carbon dioxide and Silicon dioxide dot and cross diagrams- not the giant covalent networks

There has actually been a couple of 1 markers theyv tended to throw in every now and then- such as one similar one for Paraffin wax in the past- Where it asked what was in the wick and all you had to say was something sensible such as hydrocarbon, or fuel

If you understand what i mean


I said something about there's a silicon atom instead of a carbon atom. Also I said that silicon has 8 more innner electrons than carbon. This was a random, guess kind of answer for me and I said all I could really.
Reply 301
Avatar for cheetahs56
cheetahs56
OP
Well guys, judging by the answers posted I seem to have got nearly everything right, but I'm worried about the examiners being picky and me losing mark for not using correct vocabulary. What did you guys put for the question about Mendeleev and how scientists proved him right or something? And what about the absorption spectra questions? And the Spectometer? Lol a bit long I know but nobody seems to have asked these questions yet:biggrin::eek4:
Reply 302
Avatar for krisshP
krisshP
14
Original post by cheetahs56
Well guys, judging by the answers posted I seem to have got nearly everything right, but I'm worried about the examiners being picky and me losing mark for not using correct vocabulary. What did you guys put for the question about Mendeleev and how scientists proved him right or something? And what about the absorption spectra questions? And the Spectometer? Lol a bit long I know but nobody seems to have asked these questions yet:biggrin::eek4:


Use mark scheme answers!

For the Mendeleev first question Is said for elements yet to be discovered. For the second question on how it was a good decision, I said that newly discovered elements fitted these gaps due to their chemistry and properties.

For atomic absorption spectrum apperance I said line spectra with black lines on a coloured background.
Reply 303
Avatar for cheetahs56
cheetahs56
OP
Original post by krisshP
Use mark scheme answers!

For the Mendeleev first question Is said for elements yet to be discovered. For the second question on how it was a good decision, I said that newly discovered elements fitted these gaps due to their chemistry and properties.

For atomic absorption spectrum apperance I said line spectra with black lines on a coloured background.


Yeah I said the same for both :biggrin::biggrin:
Reply 304
Avatar for krisshP
krisshP
14
Original post by cheetahs56
Yeah I said the same for both :biggrin::biggrin:


What did you say for the question on dot and cross diagram difference between carbon dioxide and silicon dioxide???
(edited 11 years ago)
Original post by cheetahs56
Yeah I said the same for both :biggrin::biggrin:


No, no there was a 3 marker on absorption
What were your points for this?

There was also a properties question i remember doing, but i dont remember the question. im pretty sure i named a type of compound though!!
Reply 306
Avatar for cheetahs56
cheetahs56
OP
Original post by NielsBohrsDad
No, no there was a 3 marker on absorption
What were your points for this?

There was also a properties question i remember doing, but i dont remember the question. im pretty sure i named a type of compound though!!


For spectrum:
1. Electron has absorbed energy and moved up energy as it is excited
2. The energy is electromagnetic radiation, and each element has fixed energy shells.
3. The difference in energy levels is different for each element.
4. Hence the frequency of the energy absorbed is different for each element, so each spectra is unique.

Would this get me the marks?


Original post by krisshP
What did you say for the question on dot and cross diagram difference between carbon dioxide and silicon dioxide???


I put that one is ionic and the other covalent (but I know this is wrong now). I think Silicone has a dative covalent bond? What did you put?
Original post by cheetahs56
For spectrum:
1. Electron has absorbed energy and moved up energy as it is excited
2. The energy is electromagnetic radiation, and each element has fixed energy shells.
3. The difference in energy levels is different for each element.
4. Hence the frequency of the energy absorbed is different for each element, so each spectra is unique.

Would this get me the marks?




I put that one is ionic and the other covalent (but I know this is wrong now). I think Silicone has a dative covalent bond? What did you put?


yeah, should do.i did something along the same lines- i said the atoms absorb a photon(hope thats right)
then they get promoted to higher levels, and as they do so they absorb certain frequencies eqal to the gap in energy levels. because frequncy is related to the levels by E=Hv, different elements absorb different frequencies.

but come to think of it i would have said this- ive kinda forgotten what ive wrote now but it most likely would have been the 3 main ideas about how they exist in definitive levels

And i think you are right with the silicone and dative bond i had a look at the dot and cross diagrams lol
Reply 308
Avatar for cheetahs56
cheetahs56
OP
Original post by NielsBohrsDad
yeah, should do.i did something along the same lines- i said the atoms absorb a photon(hope thats right)
then they get promoted to higher levels, and as they do so they absorb certain frequencies eqal to the gap in energy levels. because frequncy is related to the levels by E=Hv, different elements absorb different frequencies.

but come to think of it i would have said this- ive kinda forgotten what ive wrote now but it most likely would have been the 3 main ideas about how they exist in definitive levels

And i think you are right with the silicone and dative bond i had a look at the dot and cross diagrams lol


Yeah I think photon will be accepted:wink: As long as you said the same sort of things they will accept.... what others questions were you unsure about?

Nobody in my school knew the silicone question...
Reply 309
Avatar for zippy103
zippy103
what answers ??, where can i find the marskscheme
Original post by cheetahs56
Yeah I think photon will be accepted:wink: As long as you said the same sort of things they will accept.... what others questions were you unsure about?

Nobody in my school knew the silicone question...


Because i sat there in that exam thinking to myself, it says energy here and radiation- should i write photon? because photons always part of the mark scheme wen i used to write energy lol!!

What about the mass spec question
for these Two 3 and 4,markers my answers were so muddled up hope the examiner understands lol.
Reply 311
Avatar for zippy103
zippy103
Original post by krisshp
use mark scheme answers!

For the mendeleev first question is said for elements yet to be discovered. For the second question on how it was a good decision, i said that newly discovered elements fitted these gaps due to their chemistry and properties.

For atomic absorption spectrum apperance i said line spectra with black lines on a coloured background.
what mark scheme answers ?! Where are they ?!
Reply 312
Avatar for krisshP
krisshP
14
Original post by cheetahs56
For spectrum:
1. Electron has absorbed energy and moved up energy as it is excited
2. The energy is electromagnetic radiation, and each element has fixed energy shells.
3. The difference in energy levels is different for each element.
4. Hence the frequency of the energy absorbed is different for each element, so each spectra is unique.

Would this get me the marks?




I put that one is ionic and the other covalent (but I know this is wrong now). I think Silicone has a dative covalent bond? What did you put?

Read post 328 in this thread for what I wrote down
Reply 313
Avatar for krisshP
krisshP
14
Original post by zippy103
what mark scheme answers ?! Where are they ?!


Lol. PAST PAPER mark scheme
Reply 314
Avatar for Bluesky11
Bluesky11
Can anyone predict the grade boundaries?
Reply 315
Avatar for cheetahs56
cheetahs56
OP
Original post by NielsBohrsDad
Because i sat there in that exam thinking to myself, it says energy here and radiation- should i write photon? because photons always part of the mark scheme wen i used to write energy lol!!

What about the mass spec question
for these Two 3 and 4,markers my answers were so muddled up hope the examiner understands lol.


For Mass Spec I put:

1. Sample is Vaporised and passed in through sample inlet.
2. Bombarded with high-energy electrons, an electron is knocked off- ionises it,
3. Accelerated by an electric field.
4. Passes through drift region to detection by the ion detector- time measured to get to detector.
5. Larger isotopes will take longer to reach than smaller isotopes.

Think that should be 5 marks?


Original post by krisshP
Read post 328 in this thread for what I wrote down


Not sure if they will allow that- depends how picky they are:s-smilie:
Reply 316
Avatar for krisshP
krisshP
14
Original post by cheetahs56
For Mass Spec I put:

1. Sample is Vaporised and passed in through sample inlet.
2. Bombarded with high-energy electrons, an electron is knocked off- ionises it,
3. Accelerated by an electric field.
4. Passes through drift region to detection by the ion detector- time measured to get to detector.
5. Larger isotopes will take longer to reach than smaller isotopes.

Think that should be 5 marks?




Not sure if they will allow that- depends how picky they are:s-smilie:

What about saying defection by an electric field for mass spectroscopy
Reply 317
Avatar for Phteven
Phteven
15
I've used the correct method on the energy density question but I've got the wrong answer because I miscounted the number of carbons in the skeletal formula before -.- Will i get ecf and get all 3 marks for it? I'm panicking!!
Original post by cheetahs56
For Mass Spec I put:

1. Sample is Vaporised and passed in through sample inlet.
2. Bombarded with high-energy electrons, an electron is knocked off- ionises it,
3. Accelerated by an electric field.
4. Passes through drift region to detection by the ion detector- time measured to get to detector.
5. Larger isotopes will take longer to reach than smaller isotopes.

Think that should be 5 marks?




Not sure if they will allow that- depends how picky they are:s-smilie:


I think i did something similar, only with mine i said after the ionisation bit- that the ions are accelerated by an electric field to ensure they all have the same kinetic energy- and because of this increased energy, it meant that only the mass could affect the time taken to reach the detector- i vaguely spoke about the detector and didnt call it an ion detector- i called it a detector lol!! then i just said it meant that lighter ions reached first.

And also the empirical formula of cerium oxide- i really dont see where i went wrong i did 81.4/240.1(seeing as there was 2 cerium atoms in the ce2o3) and 18.6/48(3 oxygens in the ce2o3)
and my final answer was ce506 which nobody got!!!
Lol!!
the main point of tis question is that you definitely talk about kinetic energy and mass- so therefore i reckon it would have focussed on the ion detector and the acceleration area
i didnt really mention them i jus talked about the processes e.g the ions are then accelerated by an electric field and e.g ions are detected(lighter first)- im guessing that gets me a mark as AW(alternatively worded)?

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