A Question abou t Mass Changes in Chemical Reactions

[Death]

Okay in a closed system undergoing chemical reaction, the mass of the reactants = the mass of the products. The overall mass does not change regardless of what is happening in the system (Law of Conservation of Mass).

What about something like this?

When 250kg of wood is burned in a fireplace, about 5 kg of ashes are collected when the reaction is finished. How can you account for this in terms the Law of Conservation of Mass?

I don't think you can because it isn't a closed system? And wouldn't a lot of the wood be carried up and away by air and combustion? Where is the other 245 kg?

 

[redgreenblue]

If there is 245kg missing from the end product, it is either in gas state or the solid remaining is lifted away by the gas produced. There is no unaccounted matter.

 

[Firebert]

You can't account for it because it is a very open system. The rest of it either was taken away through the chimney, or in a gas state. The very concept of a closed system cannot facilitate fire, because fire requires oxygen to fuel it.

 

[WoapGang]

I believe it would be 245kg of Gas that came from the Wood. (Strangely enough, i just learned this a week ago. No lie)

 

[Death]

Yea, this is exactly what I was thinking, Firebert. Because it is an open system, the matter can't be contained in one place. Although the rest was carried away as a gas up the chimmney.

 

[Firebert]

Yeah, and I mean, think of the ashes that float out through the front of the fireplace, too!