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How to make up a rxn mixture to 250 cm3

Question 21 a(iii)
https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Past-Papers/Edexcel-IAL/Unit-5/June%202015%20(IAL)%20QP%20-%20Unit%205%20Edexcel%20Chemistry%20A-level.pdf

and the same question in a different year 21bi
https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Past-Papers/Edexcel-IAL/Unit-5/January%202014%20(IAL)%20QP%20-%20Unit%205%20Edexcel%20Chemistry%20A-level.pdf

MS: https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Past-Papers/Edexcel-IAL/Unit-5/January%202014%20(IAL)%20QP%20-%20Unit%205%20Edexcel%20Chemistry%20A-level.pdf

Why is a conical flask rejected in the 2nd paper and used in the 1st one ?
(edited 5 years ago)
Original post by Leah.J
Question 21 a(iii)
https://qualifications.pearson.com/c...e_20150615.pdf

and the same question in a different year 21bi
https://qualifications.pearson.com/c...e_20140121.pdf

https://qualifications.pearson.com/c...c_20140306.pdf
Why is a conical flask rejected in the 2nd paper and used in the 1st one ?

Not sure if it's just me but when I click those links I get redirected to https://qualifications.pearson.com/en/home.html
Reply 2
Avatar for Leah.J
Leah.J
OP
13
Original post by BobbJo
Not sure if it's just me but when I click those links I get redirected to https://qualifications.pearson.com/en/home.html

I tried changing the links. Do they work now ?
Original post by Leah.J
I tried changing the links. Do they work now ?


Yes (last 2 links are the same)

The ms for the 2nd: "...Transfer solution to a volumetric /graduated flask (1) ...."

The ms for the first: "...Transfer the reaction mixture to a (250 cm3) volumetric/graduated flask..."

In both you need to use a volumetric flask. A volumetric flask is used to make up standard solutions (solutions of known concentrations). It was necessary to use a volumetric flask.
Reply 4
Avatar for Leah.J
Leah.J
OP
13
Original post by BobbJo
Yes (last 2 links are the same)

The ms for the 2nd: "...Transfer solution to a volumetric /graduated flask (1) ...."

The ms for the first: "...Transfer the reaction mixture to a (250 cm3) volumetric/graduated flask..."

In both you need to use a volumetric flask. A volumetric flask is used to make up standard solutions (solutions of known concentrations). It was necessary to use a volumetric flask.

Right, I'm talking about the very first step , which is the one where I add a solid to a beaker and then add the acid ( the 2nd step would be to transfer the mixture to a volumetric flask which is mentioned in both ) . The mark scheme in the 2nd paper says add solid to a beaker + reject conical flask ... but the question in the 1st paper carries out the rxn of the solid Fe with H2SO4 in a conical flask so why is a conical flask rejected in the 2nd paper but used in the 1st ?
Original post by Leah.J
Right, I'm talking about the very first step , which is the one where I add a solid to a beaker and then add the acid ( the 2nd step would be to transfer the mixture to a volumetric flask which is mentioned in both ) . The mark scheme in the 2nd paper says add solid to a beaker + reject conical flask ... but the question in the 1st paper carries out the rxn of the solid Fe with H2SO4 in a conical flask so why is a conical flask rejected in the 2nd paper but used in the 1st ?

For the first paper, you have to transfer the reaction mixture already in the conical flask. They already gave the first step as using a conical flask as the initial reaction is performed in a conical flask. So the use of it has to be respected as it is given in the question.

In practice you use a beaker because it's much easier to stir. This shows the preparation of a standard solution: https://www.youtube.com/watch?v=g5azAxTywgc Notice that in the procedure, a beaker is used, not a conical flask.

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