Edexcel As Chemistry Unit 3B

Hey! Does anyone know any website that can explain the different types of apparatuses needed for the different experiments, somehow I always get stuck on those questions.

Second one, and actually many people make this mistake.
I believe you multiply by 2 when your solution is a combination of 2 individually measured volumes.

HAHAHAHAH yeah, I am! lol.

Does anyone have the 2012 January paper?

any 1 whose done the jan 2010 paper..plzzzz help me with the question no.4(f).......itz about percentage yield..but it deals with mols and volume

1 mol alcohol = 1 mol chloroalkane
0.2 mol alcohol = 0.2 mol chloroalkane

therefore, maximum mass of chloroalkane = (0.2 * 92.6) g
= 18.5 g

therefore, maximum volume of chloroalkane = (18.5 / 0.842) cm^3
= 22.0 cm^3

percentage yield = (18.7 / 22.0 * 100) %
= 85.0 %

1 mol alcohol = 1 mol chloroalkane
0.2 mol alcohol = 0.2 mol chloroalkane

therefore, maximum mass of chloroalkane = (0.2 * 92.6) g
= 18.5 g

therefore, maximum volume of chloroalkane = (18.5 / 0.842) cm^3
= 22.0 cm^3

percentage yield = (18.7 / 22.0 * 100) %
= 85.0 %

Can anyone explain the reason behind the answer for question 3(d)(v) of January 2010?

Yeah coz u see the concentration doubles to 2moldm-3 from 1moldm-3 previously!
so temperature doubles :P

dont jus look at 50cm3 and 25cm3!> i did tht too first! :P

Can anyone explain when there should be a stopper in a reflux condenser?
In May 2010,question 4.b,the mark scheme says to not use a stopper,why?