MagicSophie Posted January 3, 2011 Report Share Posted January 3, 2011 Can somebody tell me, is the mass just the mass of the fuel before you start burning it, or do you have to take into consideration the starting and ending masses?Or do I have this completely wrong?I would greatly appreciate any help you can give me. I'm stuck, and I have an IA due in the morning...EDIT: Erp. I'm thinking this paper I have says I should be measuring the mass of the water I'm heating, not the fuel. This is terrible, I feel so stupid. Reply Link to post Share on other sites More sharing options...
kiwi.at.heart Posted January 3, 2011 Report Share Posted January 3, 2011 Anyone feel free to correct me if I have remembered wrong but m is the mass of the water, which my teacher told me for water you just convert ml to g (eg 200ml=200g) Reply Link to post Share on other sites More sharing options...
MagicSophie Posted January 3, 2011 Author Report Share Posted January 3, 2011 Ok, that's good, that's how I did it, but is the mass/volume of the fuel good for nothing? Because I seem to remember that there were other people weighing their little alcohol burner things. Maybe I'm just crazy, I don't know.Thanks, though, this was really helpful. ^.^ Reply Link to post Share on other sites More sharing options...
kiwi.at.heart Posted January 3, 2011 Report Share Posted January 3, 2011 A few months ago we did a prac on enthalpy change using different alcohols. I'm just looking back on it, we used mcT to find out how much energy it took to heat up the water to a certain point, and then used the difference of mass of the alcohols to figure out how much energy was given by it. Then we did some other calculations to figure out how much energy per mole is released by each alcohol. I don't know if this sounds anything like your IA but I'm just throwing out an idea why people were weighing the mass of the fuels. Reply Link to post Share on other sites More sharing options...
MagicSophie Posted January 3, 2011 Author Report Share Posted January 3, 2011 Yeah, that makes sense, actually, a few people were using different alcohols as their variable. My variable was time.Ok, thanks very much for your help.: ) Reply Link to post Share on other sites More sharing options...
Drake Glau Posted January 3, 2011 Report Share Posted January 3, 2011 Should be your start mass. The equations measures the amount of heat/energy for the whole system, so all the mass. Take boiling water for example. The amount of heat you put into the water will not equal the amount of energy that left with the water vapor, the water is still hot but still there. So it's not the difference in masses, its your total start mass. Reply Link to post Share on other sites More sharing options...
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