Question: if you were to put a a type of rock in a air tight room and slowly turn up the heat what would happen ?

Gemma Purser answered on 28 Jun 2012:

Good questions geek52!! 🙂 It all depends on what type of rocks you have got and how much you heat up the room!

Well firstly have you sucked all the air out of the room under vacuum? if not there will still be air in when you opened the door to put in your sample, even if the room is air tight once you shut the door.
So I guess we need to know what air is so we can see what reactions could happen!

Air is made up of nitrogen, oxygen, carbon dioxide, argon, a little bit of water vapour and some other gases in tiny amounts including things like helium, hydrogen and methane (but this can change depending on if people are in the room, hehehehe!!)

So the most reactive parts of air are the carbon dioxide and water.
Water and carbon dioxide can react and then this can dissolve minerals like calcium carbonate in limestone.
Carbon dioxide can react with minerals such as calcium silicates to form calcium carbonates in things like cements.

Next there is the temperature part!
Most rocks that you get out of the ground contain some water. So as you start to heat it up this water will evapourate and the rock will dry out. If you weigh the rock before and after you can work out what we call its moisture content, how much water was in it to start with.

Rocks that contain alot of clays can hold lots of water and even with a little bit of heating the clays can dry out and the rock would start to shrink and maybe even crack (fracture).

Now if you were to have limestone in your room and turn up the temperature to above 1000 degrees celsius then it would breakdown (decompose) and release carbon dioxide as a gas and leave you with a compound called calcium oxide (sometimes called quick lime, used in the building to make cement).

If you had a lump of coal in your room and no air and heated it up to 2000 degrees celcius you would make a thing called coke.

If you had an ore (a type of rock containing metal) called hematite (iron ore) and you turned up the temperature even higher then you could get liquid metals (especially if you left the coke and limestone from our other experiments in their too)

So just want to show you that there are lots of experiments can be done and lots of processes and data calculated just by changing two things such as temperture and rock type.

Hope that wasn’t too much to read!! 🙂