Current Year 13 thread Mark I (2014-2015)

Same. I know I'm gonna fail

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Reply 9582

Original post by rachelc142

I. am. so. fed. up. with. A. Levels.

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3 more and then I'm done!
And one of them's tomorrow
We'll see how it goes

Reply 9583

Enigma Machine

Original post by 8472

Realised I post more in the year 10 thread than my own year group thread. :blush:

Interested, would people say that their revision technique has gotten better each year?

Umm, seeing as I didn't really revise for my GCSEs I guess you could say my technique has improved over the years... :lol:

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Reply 9584

Enigma Machine

Original post by rachelc142

I. am. so. fed. up. with. A. Levels.

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Baelieve in yourself and persevere!

Same. I know I'm gonna fail

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u too son, baelieve in yourself mate (Y)

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Reply 9585

_Caz_

10

Original post by rachelc142

I. am. so. fed. up. with. A. Levels.

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I know that feel. Every time I try to do something I just want to sleep.

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Reply 9586

Skill Twix

Original post by binarythoughts

Either 2340 or 2360 can't remember haha.
I'm the eldest so I have no one to give me advice in that respect

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Original post by Princepieman

You deffo should have given it a punt. I got 2250 but decided (foolishly) not to apply.

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So we destroyed SATS eh?

Reply 9587

Skill Twix

Original post by _Caz_

I know that feel. Every time I try to do something I just want to sleep.

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We are similar.I've got an exam in 6 days.I've been sleeping for 10 hours lol!

Reply 9588

Finished S2 today and it went grrrreat!
2 more exams to go - can't wait to finish!

Reply 9589

Red Fox

11

Original post by The Clockwork Apple

Finished S2 today and it went grrrreat!
2 more exams to go - can't wait to finish!

Mine haven't even started :emo:

.

Reply 9590

radhikagulati

9

Yo sorry for being really annoying again but you guys seem to be really good at chemistry!

I just wanted to ask why do some carboxylic acids, e.g. lactic acid, become cyclic esters when they are heated with sulphuric acid? What's this type of reaction called? I've looked in the textbook but I can't find an answer and my teachers aren't very helpful :frown:

(

Reply 9591

Saracen's Fez

Original post by radhikagulati

Yo sorry for being really annoying again but you guys seem to be really good at chemistry!

I just wanted to ask why do some carboxylic acids, e.g. lactic acid, become cyclic esters when they are heated with sulphuric acid? What's this type of reaction called? I've looked in the textbook but I can't find an answer and my teachers aren't very helpful :frown:

(

I think lactic acid has an -OH group as well as a -COOH, so it is an alcohol as well as an ester.

I couldn't tell you what the reaction is called though.

Reply 9592

zed963

16

Original post by radhikagulati

Yo sorry for being really annoying again but you guys seem to be really good at chemistry!

I just wanted to ask why do some carboxylic acids, e.g. lactic acid, become cyclic esters when they are heated with sulphuric acid? What's this type of reaction called? I've looked in the textbook but I can't find an answer and my teachers aren't very helpful :frown:

(

When you react and OH with a COOH, the bond formed is an ester bond and the process is normally called esterification.

I'm not sure you need to know why they become cyclic because AQA don't but if I had to take a guess it'd probably be to do with stability or something.

Reply 9593

radhikagulati

9

Original post by zed963

When you react and OH with a COOH, the bond formed is an ester bond and the process is normally called esterification.

I'm not sure you need to know why they become cyclic because AQA don't but if I had to take a guess it'd probably be to do with stability or something.

There was an esterification question on lactic acid and I drew a normal ester but the mark scheme came up with this weird cyclic structure so I'm vvv confused :frown:

And Im doing OCR Salters not AQA unfortunately :frown:

(

Reply 9594

zed963

16

Original post by radhikagulati

There was an esterification question on lactic acid and I drew a normal ester but the mark scheme came up with this weird cyclic structure so I'm vvv confused :frown:

And Im doing OCR Salters not AQA unfortunately :frown:

(

Interesting,

Do you have a pic of the structure?

This might help http://www.chemistryrules.me.uk/candrands/carboxylicacids.htm

(edited 8 years ago)

Reply 9595

radhikagulati

9

Thanks for the link :smile:

And it was question 2e in this paper: http://www.ocr.org.uk/Images/131296-question-paper-unit-f335-chemistry-by-design.pdf

x

Reply 9596

Original post by radhikagulati

Thanks for the link :smile:

And it was question 2e in this paper: http://www.ocr.org.uk/Images/131296-question-paper-unit-f335-chemistry-by-design.pdf

x

Yes it forms a cyclic structure! They each have at least one -OH and one -COOH group. It's one of the trickier questions

Reply 9597

cerlohee

16

Original post by radhikagulati

Yo sorry for being really annoying again but you guys seem to be really good at chemistry!

I just wanted to ask why do some carboxylic acids, e.g. lactic acid, become cyclic esters when they are heated with sulphuric acid? What's this type of reaction called? I've looked in the textbook but I can't find an answer and my teachers aren't very helpful :frown:

(

Could this be the carboxylic acid acting as a dimer? If it is, it's because hydrogen bonds are formed between the oxygen of the carbonyl carbon and the hydrogen of the OH. Here's the link http://en.wikipedia.org/wiki/Dimer_%28chemistry%29

No idea about the heating with H2SO4 part tho

Reply 9598