Conservation of mass

[jfholm]

I need some help from you math genius' on the forum. Physics question here. Is there conservation of mass in a running engine when it comes to air/fuel mixture going through the engine. In other words do we lose mass when it is burned and goes out the exhaust ot does mass stay the same?

Things we know:
1: System volume changes due to piston moving and compressing a/f mixture but at that point mass should be the same.
2: System volume temp drastically changes once burned and exits engine via exhaust system.
3: Speed of sound drastically changes in system volume due to temp getting hotter in exhaust track.
4: Pressure of system volume is much greater after burning but starts to diminish once exhaust valve opens.

What I want to know is does the mass change due to the burn and conversion of pressure, heat etc. to a working force. We lose a lot of heat to cooling system and surrounding metal. If there is a loss of mass how does it effect the outgoing system volume?

John

[86rocco1]

Chemical reactions conserve mass, combustion is a chemical reaction. I don't see how mass would be consumed after all it's an IC engine not a nuclear reactor so I'd say "Yes, mass is conversed".

[Tony]

What goes in comes out.

If it did not, the engine would either have to continually gain or lose total mass as it runs.
Energy is given up by the combustion process, but matter is neither created or destroyed in the process, just changed in energy level and chemistry (+heat and motion).

[jfholm]

Now you guys know why I failed chemistry What I should have talked about more is weight. I am trying to determine if the weight changes and how does this affect the exhaust flow compared to the intake as far as innertia? Am I worrying about something that is negligable?

John

[jfholm]

I sort of answered my own question to this over in the wet flow area :p

John

[Tony]