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OCR Salters F334 Chemistry of Materials (26/01/2011)

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Pt electrode is also used in cells where there are only ions used (Fe2+ to Fe3+ and e-), since there's nothing to be used as the electrode. Pt is used because it's inert and conducts electricity.

Reply 141

smj14

aaaaah, im really confused when to put moderately concentrated HCL for reagents, and when to put concentratedc H2SO4 or dilute acid etc.. help please?!

Reply 142

AGM

Esterification reactions = Concentrated Acid
Hydroysis of esters = Dilute Acid
Hydrolysis of amides = Moderately concentrated acid/or alkali

Reply 143

twinkabell_92

could anyone......... my hero state the conditions and reagents for all the recations/mechanisms we need to know

also when a something in diluted in a titration like from 25cm to 250cm how to do you 'adjust' your calculations
sorry about the lack of technical terms/poor descrisption i am not that chemistry savvy

Reply 144

parallal

Original post by twinkabell_92

could anyone......... my hero state the conditions and reagents for all the recations/mechanisms we need to know

Esterification (making an ester from a carbocylic acid and an alcohol)
Reagent: Concentrated Sulfuric Acid
Conditions: Heat under reflux

Hydrolysis of an amide link/ester/phenol
Reagent: Moderately concentrated acid (HCl or Sulfuric acid) or alkali (NaOH)
Conditions: Heat under reflux

Oxidation of Alcohols
Primary alcohol ---> aldehyde
Reagent: Acidified Potassium Dichromate (acidified with concentrated sulfuric acid)
Conditions: Distill

aldehyde ---> carboxylic acid
Reagent: Acidified Potassium Dichromate (acidified with concentrated sulfuric acid)
Conditions: Heat under reflux

secondary alcohol ---> ketone
Reagent: Acidified Potassium Dichromate (acidified with concentrated sulfuric acid)
Conditions: Heat under reflux

And I believe that's all we need to know. Correct me if I'm wrong.

(edited 13 years ago)

Reply 145

AGM

Original post by parallal

Just to quickly add... for Oxidation of alcohols, when you are going from a primary alcohol to an aldehyde, you Distill, you don't heat under reflux.

Reply 146

del1rious

mug what are you on about yes you do.

Reply 147

parallal

Original post by AGM

Just to quickly add... for Oxidation of alcohols, when you are going from a primary alcohol to an aldehyde, you Distill, you don't heat under reflux.

Just checked my notes. You are right. I'll go fix that now.

Reply 148

username279062

Original post by smj14

aaaaah, im really confused when to put moderately concentrated HCL for reagents, and when to put concentratedc H2SO4 or dilute acid etc.. help please?!

Conc H2SO4 OR HCl to make esters from Carboxylic Acid + Alcohol
No catalyst for making esters from Phenol + Acyl Chloride, it goes at room temp.

Hydrolysing Esters (Adding a molecule back in)
Dilute H2SO4 OR preferred is an Alkali catalyst because it goes to completion (such as NaOH)

Hydrolysing Amides (to a carboxylate ion and an amine) is Moderately Concentrated Acid

Think that's all the ones that are needed :smile:

Reply 149

Darthdevidem

Does anyone else think that June 2010 paper was extremely hard?

I mean I was getting 75-80 in all the past papers till that one where I got like 69...it was so difficult!

Reply 150

username279062

Original post by parallal

Hydrolysis of an amide link/ester/phenol
Reagent: Moderately concentrated acid (HCl or Sulfuric acid) or alkali (NaOH)
Conditions: Heat under reflux

It's definately only Dilute Sulfuric they'll accept here, been caught out by that in a few past papers. Worth noting that with an alkili catalyst the reaction goes to completion too :smile:

Reply 151

username279062

Original post by Darthdevidem

Does anyone else think that June 2010 paper was extremely hard?

I mean I was getting 75-80 in all the past papers till that one where I got like 69...it was so difficult!

Yeah! That electrode potential question was horrible :|

Reply 152

joestevens2092

Any essential storylines we should have a quick read over of guys? Just read over the ethics around DNA databases, which was a past paper question

Reply 153

Mr-Joey-C

Original post by joestevens2092

Any essential storylines we should have a quick read over of guys? Just read over the ethics around DNA databases, which was a past paper question

I reckon BOS process cause i havent seen that in like the actual papers for this spec yet :smile:

Reply 154

Darthdevidem

Original post by doomhalo

Yeah! That electrode potential question was horrible :|

lol thats the one I'm doing well on. I completely flopped on Q1 and 2 though, lost 15 marks in them both combined :frown:

Reply 155

Legit

Original post by Darthdevidem

Does anyone else think that June 2010 paper was extremely hard?

I mean I was getting 75-80 in all the past papers till that one where I got like 69...it was so difficult!

June i got 77/90 or was it 74? I got in the 70s
69 is A* isnt it?

Reply 156

username279062

Original post by Darthdevidem

lol thats the one I'm doing well on. I completely flopped on Q1 and 2 though, lost 15 marks in them both combined :frown:

Yeah was pretty tricky throughout, although I imagine the boundary was a fair bit lower.

Reply 157

cORBO3

Original post by Mr-Joey-C

I reckon BOS process cause i havent seen that in like the actual papers for this spec yet :smile:

But apprantly BOS isn't listed on the spec...

Reply 158

smj14

what is bos? :s-smilie:

Reply 159

AGM

Original post by smj14

what is bos? :s-smilie:

Basic Oxygen Steeling Making Process.

All you need to know is... steel is at first full of impurities, they get rid of the sulphur with a blast of Magnesium. And get rid of other impurities like Carbon(which makes steel brittle) with a blast of oxygen. Different levels of other elements in the steel give it different properties.

Recycled steel is added to act as a coolant and a source of recycled steel.