OCR B Salter's Chemistry by Design F335 - 15th June 2015

Reply 360

Welbeck

3

dam, I put ketone, so thats 3 marks down the drain for me :frown:

Reply 361

Charletitia

3

The last question was plural suggesting that you could give an example of one of many reactions an aldehyde undergoes.. -e.g you could use NaBH4 and go back to an alcohol or go forward to a carboxylic acid.

Hence why it said 'final colour' and not 'colour change' because from an aldehyde to a carboxylic acid it still stays green.

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Reply 362

Diamond Crafter

8

I think I may have made quite a few silly mistakes. *sigh*

Reply 363

Charletitia

3

Original post by Diamond Crafter

I think I may have made quite a few silly mistakes. *sigh*

Me too haha! Me too :frown:

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Reply 364

The fish inspect

2

Original post by Solarburst

Yeah but it had no mention of enzymes being a limiting factor

Does it need to mention it, isn't just something you should know. I dunno it was like 2/3 marks no the end of the world

Reply 365

diba786

2

Original post by Charletitia

The last question was plural suggesting that you could give an example of one of many reactions an aldehyde undergoes.. -e.g you could use NaBH4 and go back to an alcohol or go forward to a carboxylic acid.

Hence why it said 'final colour' and not 'colour change' because from an aldehyde to a carboxylic acid it still stays green.

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Yup yup saiddd i said oxidation to cooh and said green :smile:

Reply 366

Minecraft27

14

Original post by Charletitia

Doesn't you mean? In pure form it's a solid so it needs to be in aqueous solution otherwise two solids won't react!

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Solids DO react!!!

It's because the anion isn't stable enough to produce sufficient amounts/concentrations of hydrogen ions to react with carbonates.

Carbonates need a strong acid to react, but butanoic acid just ain't strong enough on its own.

(edited 8 years ago)

Reply 367

Charletitia

3

Original post by Minecraft27

Solids DO react!!!

It's because the anion isn't stable enough to produce sufficient amounts of hydrogen ions to react with carbonates.

Carbonates need a strong acid to react, but butanoic acid just ain't strong enough on its own.

Fairy nuff! I bow down to your chemistry superiority.

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Reply 368

Diamond Crafter

8

I just pray that the grade boundaries are lower than last years for this year. For both exams. :crossedf:

Reply 369

Remedium

6

Original post by Minecraft27

Solids DO react!!!

It's because the anion isn't stable enough to produce sufficient amounts/concentrations of hydrogen ions to react with carbonates.

Carbonates need a strong acid to react, but butanoic acid just ain't strong enough on its own.

Butanoic acid has to be in aqueous solution to dissociate? Pure butanoic acid won't dissociate as there are no water molecules to form H30+

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Reply 370

Mars256

8

I don't mean to be awkward but is anyone making an unofficial markscheme?

Reply 371

pinkgorilla

5

Do people think that this was harder or easier than last year and any a* predictions ?

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Reply 372

Minecraft27

14

Anyone get -1162 or something like that for the enthalpy change thingy?

Reply 373

Diamond Crafter

8

Oh a topic of rant:

What was the last double page about? I haven't revised free radical reactions in ages (in hindsight I probably should have)! BUT having said that it was just ticking boxes. It threw me a little when it came up because all I kept thinking about was how annoying the boys in my class were at AS when doing the atmosphere's chapter. :noway:

Reply 374

username911777

15

Original post by Minecraft27

Anyone get -1162 or something like that for the enthalpy change thingy?

Yeyeyeyeyeyeyey

Something we agree on aha

Reply 375

Minecraft27

14

Damn it seems I have made countless silly mistakes such as putting 5 isomers when apparently it's 3.
Maybe they'll allow 5?

Reply 376

LordGaben

11

Original post by JakeDaw

I put 3 as well because the Ar values are 3 s.f. I think I got 35.0%?

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Excellent thats what I got

Reply 377

TripleAA

1

Original post by Minecraft27

Solids DO react!!!

It's because the anion isn't stable enough to produce sufficient amounts/concentrations of hydrogen ions to react with carbonates.

Carbonates need a strong acid to react, but butanoic acid just ain't strong enough on its own.

Actually, all carboxylic acid react with carbonate as taught during f334 to produce carbon dioxide etc (Test for carboxylic acid) so i dont think thats right...

Reply 378

Remedium

6

For the radicals question, no termination and one initiation?
I crossed out a few boxes and had to redo some.. Would the examiner mark the ones I ticked and not the ones I scribbled out? It was a bit messy

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