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OCR A2 CHEMISTRY F324 and F325- 14th and 22nd June 2016- OFFICIAL THREAD

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Original post by Walkerz7
Does anyone have the OCR breadth in chemistry specimen paper link like the one that we did for mocks that OCR send the teachers??


http://www.ocr.org.uk/Images/171751-unit-h032-01-breadth-in-chemistry-sample-assessment-materials.pdf
https://goo.gl/nVvgw9
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Avatar for hbk1
hbk1
2
anyone else bricking it
Yes but if you wan't the stock answers here they are.

TMS is used as the standard for chemical shift measurements

D2O undergoes proton exchange (with labile protons e.g. OH, NH)

CDCl3, a deutarated solvent, is used as it does not provide a peak
do we need to know that halogenoalkanes + NH3 (or amines) would eventually turn into a quaternary ammonium salt if NH3 is not in excess (or the halogenoalkane is in excess ) ?????? p.s. i hate spelling the word quaternary !
In TLC how do you know about the solubility of compound? Like the higher the Rf the more soluble???? idk....
got that one thx
Original post by lai812matthew
do we need to know that halogenoalkanes + NH3 (or amines) would eventually turn into a quaternary ammonium salt if NH3 is not in excess (or the halogenoalkane is in excess ) ?????? p.s. i hate spelling the word quaternary !


You'll just be able to need to say that ethanolic ammonia is in excess to prevent further substitutions

Original post by Haydenator
In TLC how do you know about the solubility of compound? Like the higher the Rf the more soluble???? idk....


the greater the solubility, the slower the component moves, cause it will be more attached to the stationary phase. Rf= distance move by component/ distance move by solvent, so Rf is smaller. and retention time longer.
Original post by lai812matthew
the greater the solubility, the slower the component moves, cause it will be more attached to the stationary phase. Rf= distance move by component/ distance move by solvent, so Rf is smaller. and retention time longer.


TLC has nothing to do with retention time. It's separation by adsorption.
Best of luck everyone 🍀
Does anyone know if dilute, excess acid or alkali is used in any of the hydrolysis reactions? It keeps popping into my head and I can't remember what it's used for!!
Original post by suibster
TLC has nothing to do with retention time. It's separation by adsorption.


lol yeah sorry. so it would be the stronger the adsorption, the component binds more strongly. travels in shorter distance. Rf= distance move by component/ distance move by solvent. therefore Rf value decreases.
(edited 7 years ago)
Good luck guys!! Hoping the h nmr is kinder than last year 😂


Posted from TSR Mobile
If in GC and the stationary phase is a solid, then it separates by adsorption right?
Original post by L'Evil Wolf
If in GC and the stationary phase is a solid, then it separates by adsorption right?


Yes, that's correct
Original post by L'Evil Wolf
If in GC and the stationary phase is a solid, then it separates by adsorption right?


Yeah
Original post by Lularose83
Does anyone know if dilute, excess acid or alkali is used in any of the hydrolysis reactions? It keeps popping into my head and I can't remember what it's used for!!


almost every reaction uses conc acid except diazotisation which uses dilute HCl i think?
Original post by lai812matthew
almost every reaction uses conc acid except diazotisation which uses dilute HCl i think?


All hydrolysis reactions use dilute acid and alkali
Original post by lai812matthew
almost every reaction uses conc acid except diazotisation which uses dilute HCl i think?


I always say you use dilute HCl for acid hydrolysis of esters

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