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Help! AS Chem PAG

We did an experiment to determine the ram of mg. we placed mg in h2so4 and measured the volume of hydrogen produced. When we placed the mg into the boiling tube containing the acid we had to remove the Bung which allowed an error in our results. Is there a way of removing this error. Is there any apparatus that would allow me to place the mg into the acid without letting in extra air.
Reply 1
Put the Mg in the bottom of a 3-necked round bottomed flask, have a septum over one of the necks, a stopper in another and your gas syringe connected to the last.

Squirt in the sulfuric acid through the septum from a syringe, accounting for whatever volume of gas this will push into the gas syringe.

Allow everything to cool to room temperature after the reaction has subsided, then measure the volume.
Original post by ishaniss
We did an experiment to determine the ram of mg. we placed mg in h2so4 and measured the volume of hydrogen produced. When we placed the mg into the boiling tube containing the acid we had to remove the Bung which allowed an error in our results. Is there a way of removing this error. Is there any apparatus that would allow me to place the mg into the acid without letting in extra air.


The thing is your losing Hydrogen gas since the reaction is fastest at the start. There are apparatus that allow you to do that, so add the magnesium onto a string and attach to the bung then lower bung, so your sealing the flask and adding the magenisum at the same time. However you now adding a third reactant -the string. The best way is to use a divided flask you put it all in and shake it, but schools don't really have these since its just a PAG don't worry about losing any gas, it don't have to be accurate, just mention it in your write up.

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