A2 OCR Chemistry B F334 - June 2015

I just said that scrap steel was magnetic so could easily be reused again. I'm sure it was incorrect though

the scrap steel is used to regulate temperatures i think , i remember seeing this question in a past paper but sounds like there were multiply reasons

Reply 481

Marseille013

1

Original post by holliejadex

What did everyone put for the 2 marker about the high resistance voltmeter having an incorrect value? excluding experimental error

I put not standard conditions (pretty sure that's right)
Not standard states (very unsure)

Reply 482

holliejadex

Original post by TikiLodge

I said how it was at 20 degrees instead of 25 but I think that might come under experimental error. I didn't know what else to put

I put that the voltmeter may not have measured the highest voltage and also that the salt bridge may not have fully connected the circuit?
Defiantly don't think I was right though - only two marks at the end of the day though I guess! :u:

Reply 483

emliche

10

What about the Dna 5 mark question. What did people put?

Reply 484

gilbertblythe

2

Original post by holliejadex

What did everyone put for the 2 marker about the high resistance voltmeter having an incorrect value? excluding experimental error

the student did the experimnt at 20 degrees when standard conditions are 25.
and, the student used only APPROX. 1moldm-3 and not exactly 1moldm-3
:smile:

Reply 485

thedontom

1

anyone remember me saying about the biology stuff coming up?...

Reply 486

LordGaben

11

Original post by BrokenS0ulz

Non standard conditions 0.1M instead of 1M and 20degrews instead of 25 degrees

Yeah to adjust temperature of furnace

Ah hello. Yh I wrote that aswell. Made the most foolish mistakes in this paper haha. Maybe dropped 10-15 marks. Was actually pretty hard compared to all other years. How did u find it

Reply 487

Denarkas

1

Original post by Beasttty

everyone is saying tri on here

I put di

The spectra showed a peak around 3600, which could only be for an OH group, right? The tri monomer didn't have any OH groups.

Reply 488

holliejadex

Original post by emliche

What about the Dna 5 mark question. What did people put?

I put that the bases bond via hydrogen bonds. 2 between A and T and then 3 between C and G. For replication I said about DNA polymerease and helicase catalysing the separation of stands that then mRNA synthesising the strand by joining via the complementary bases?
Not sure though :frown:

Reply 489

TikiLodge

1

Original post by emliche

What about the Dna 5 mark question. What did people put?

I put how A-T has two bonds while C-G has 3 therefore it acts as a copying mechanism because each base can only bond to their corresponding pair. I've never seen a question like that come up before though...

Reply 490

LordGaben

11

Original post by emliche

What about the Dna 5 mark question. What did people put?

Um to summarise I wrote hydrogen bonds between the 2 pairs of bases. 2 between A and T and 3 between C and G. During replication H bonds break separating strands and complementary bases make new hydrogen bonds to exposed bases and new strand is synthesised allowing DNA to replicate

Reply 491

student1508

Okay what did everybody say for the weird one on like explain reasons people might give for having their DNA tested, having it on a database and having it removed?

Reply 492

The fish inspect

2

Original post by holliejadex

I put that the bases bond via hydrogen bonds. 2 between A and T and then 3 between C and G. For replication I said about DNA polymerease and helicase catalysing the separation of stands that then mRNA synthesising the strand by joining via the complementary bases?
Not sure though :frown:

That's right i think, but it was talking about DNA replication so I think mRNA isn't involved. You had mention free neucleotides

Reply 493

BrokenS0ulz

3

Original post by LordGaben

Ah hello. Yh I wrote that aswell. Made the most foolish mistakes in this paper haha. Maybe dropped 10-15 marks. Was actually pretty hard compared to all other years. How did u find it

I think it was very hard in comparison to other years papers. I think I've probably dropped about 10-15 marks too. Wasn't sure what to out for the gas valve thing. I just said to stop oxygen getting in so iron 2+ isn't oxidised. :/ what did u get for the ion that iodide reacts with?

Reply 494

thedontom

1

That DNA question was do-able but the different amounts of hydrogen bonding was just there to give the biologists a hand..

Reply 495

TikiLodge

1

Original post by student1508

Okay what did everybody say for the weird one on like explain reasons people might give for having their DNA tested, having it on a database and having it removed?

I said how people would give it for future generations of family, for people who had committed crimes and people who were suspected of crimes.

Reply 496

LordGaben

11

Original post by BrokenS0ulz

I think it was very hard in comparison to other years papers. I think I've probably dropped about 10-15 marks too. Wasn't sure what to out for the gas valve thing. I just said to stop oxygen getting in so iron 2+ isn't oxidised. :/ what did u get for the ion that iodide reacts with?

It was the more postive half cell that reacted with the I-. Did you give your answer to 2sf or 3sf in maths. I gave it to 2. Got 97%. Messed up that question with the gas valve so badly but it was so simple 😭😭

Reply 497

TikiLodge

1

Original post by BrokenS0ulz

I think it was very hard in comparison to other years papers. I think I've probably dropped about 10-15 marks too. Wasn't sure what to out for the gas valve thing. I just said to stop oxygen getting in so iron 2+ isn't oxidised. :/ what did u get for the ion that iodide reacts with?