[Barooo50]

I have a mini homework in 4 hours and what I need to do is to determine laborative the molemass of magnesium,
I had an idea of maybe letting it oxide with oxygen in a sealed enviroment but that makes no sense as I could be trying forever because i "dont" know the molemass of magnesium but I do it is 24,3 however  its supposed that you dont know and have to find a way

[Hunter2]

You can dissolve a certain amount in hydrochloric acid and collect the volume of hydrogen. Over the molar volume or ideal gas equation you can get the moles. This can converted to the moles of magnesium with the chemical reaction equation and with your given mass you can calculate the molecular weight