Chemistry Paper 5 (CIE): What is divided flasks?

[sonatinalai]

I came across 'divided flasks' from one of the examiner reports.

In many plan questions from the old paper 5, candidates were asked to show how they would mix
reagents without loss of gas from the apparatus. Many candidates were therefore well drilled in the
use of “divided flasks”, placing one reagent in a small container inside the reaction vessel,
suspending one reagent when assembling the apparatus etc.

Quoted from ER May/June 2007.

Could anyone explain this? Especially the principles, how it works...

[Gaz]

I came across 'divided flasks' from one of the examiner reports.

In many plan questions from the old paper 5, candidates were asked to show how they would mix
reagents without loss of gas from the apparatus. Many candidates were therefore well drilled in the
use of “divided flasks”, placing one reagent in a small container inside the reaction vessel,
suspending one reagent when assembling the apparatus etc.

Quoted from ER May/June 2007.

Could anyone explain this? Especially the principles, how it works...

Well, the question states that the volume of hydrogen is to be recorded and used to determine the rate of the reaction. In such a scenario, usually the examiners want you to take precautions so that no gas escapes and thus does not get recorded. Some might say that the magnesium ribbon is dropped into the acid and then quickly covered with a stopper or something. This is where your divided flasks come in. A divided flask (test-tube) is used to ensure that the reaction does not start until all the apparatus is assembled and gas tight. It basically works by keeping the two reagents separated from each other until you are ready to begin. To start, the flask is shaken, causing the reactants to come into contact and setting off the reaction. I couldn't find a picture of it, but Ill post one if i can find it. Hope it helps.

[AndrewCedric]

Only a flask that is divided by a glass in between.

[hira]

please help with this question

M/J 08 Q2  F

how are we suppose to draw contruction lines on the graph to drive values.

[AndrewCedric]

please help with this question

M/J 08 Q2  F

how are we suppose to draw contruction lines on the graph to drive values.

Draw a triangle-like line to find gradient.

[sonatinalai]

Thanks for the help! So let me summarise....

A 'divided flask' is a flask which has a thin sheet of glass separating its content into compartments, so that reagent in each compartment would not be in contact before the apparatus is assembled completely, eg. air-tight condition.
To start experiment, shake the 'divided flask' so that the glass will no longer separate the reagents, thus starting off the reaction.

Will that be fine?