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Edexcel AS level Unit 3B: Chemistry Laboratory Skills I 10/05/2016

Haven't been to the lab once during the entire year. I know absolutely nothing. How are you guys studying for it? Any tips?
Learn the tests and the most common reactions. Some organic and group 2 7 may help. But most importantly... past papers. I got a b in the mock but i want to get an a next week. When is your exam ? Mine is on tuesday
(edited 7 years ago)
Reply 2
Original post by ertzgrand
Learn the tests and the most common reactions. Some organic and group 2 7 may help. But most importantly... past papers. I got a b in the mock but i want to get an a next week. When is your exam ? Mine is on tuesday


My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.
Original post by Electrify
My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.


Just go trough them in the book, honestly i don't remember any of the practicals i've done this year. As long as you are good at reasoning and confident with your calculations you should be ok.
Someone help me with the use of Potassium/Sodium Manganate and dichromate. When should I use each and what will be the results?

NOTICE ME SENPAII
Reply 5
Senpai has noticed you!
Well u see Mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a Di-Alcohol. In case of dichromate in our AS we use them in preparation of Ketone, Aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps :smile:

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Reply 6
Original post by daddydevil
Someone help me with the use of Potassium/Sodium Manganate and dichromate. When should I use each and what will be the results?

NOTICE ME SENPAII


there are various uses of these
potassium dichromate is used with dilute h2so4 to oxidise a primary alcohol to an aldehyde or a carboxylic acid and changes from orange (cr2o7)2- to green (Cr)3+
potassium manganate is used to test for SO2 or an alkene and changes from purple to colorless in both cases
Original post by -akuma-
senpai has noticed you!
Well u see mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a di-alcohol. In case of dichromate in our as we use them in preparation of ketone, aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps :smile:

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Original post by raza1999
there are various uses of these
potassium dichromate is used with dilute h2so4 to oxidise a primary alcohol to an aldehyde or a carboxylic acid and changes from orange (cr2o7)2- to green (cr)3+
potassium manganate is used to test for so2 or an alkene and changes from purple to colorless in both cases


you both. I labh u <3
Original post by Electrify
My problem is with the practicals, preparing organic compounds, titrations, salts etc. I haven't done a single experiment in my life lol. Mine is on Tuesday too.


lol u dont need any! just focus on the pastpapers and memo the method.. i never took any lab class seriously :tongue:
Original post by -Akuma-
Senpai has noticed you!
Well u see Mangnate is a strong oxidizing agent and we usually use it during the conversion of any alkene to a Di-Alcohol. In case of dichromate in our AS we use them in preparation of Ketone, Aldehydes (and carbooxylic acids as well) we use a milder oxidation agent(dichromate) so that the alcohol is not completely oxidized before we have the chance to distill it off. Hope it helps :smile:

Posted from TSR Mobile

thanks! and we always use h2so4 when oxidising.
How did the paper go?
What's a test for water vapour? -_-
What reagent and conditions were needed for converting that halogenoalkane to an alkene?
Did you get enthalpy change for CH3OH as somewhere around 400-ish?
Enthalpy change from graph was -1800.
Reply 11
Original post by azefayuu
How did the paper go?
What's a test for water vapour? -_-
What reagent and conditions were needed for converting that halogenoalkane to an alkene?
Did you get enthalpy change for CH3OH as somewhere around 400-ish?
Enthalpy change from graph was -1800.


Blue cobalt chloride paper turns pink
Alcoholic KOH and reflux
Yes
No, it was around 1200-1250

My answers ^^
Original post by Electrify
Blue cobalt chloride paper turns pink
Alcoholic KOH and reflux
Yes
No, it was around 1200-1250

My answers ^^


Ayyyyyyy,same
Hard paper, wasn't it ??
Reply 13
Original post by omar5478
Ayyyyyyy,same
Hard paper, wasn't it ??


Decent & different.
Original post by Electrify
Decent & different.

Agreed
What was the answer for the very last question? The one where we were asked to calculate the percentage?
Original post by daddydevil
What was the answer for the very last question? The one where we were asked to calculate the percentage?

I got 41 but I am pretty sure it is wrong

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