The scale weight of the container doesn't increase, you made that up. The original weight of water and gasoline get converted to CO2 (and water, and some other stuff) with the measurable weight of the new CO2 as stated.
Yes I made that up for a reason. To repeat for the 10th time, and THIS time I'll go slow, people are NOT getting it. Read each sentence s l o w l y. Remember...this is from "experts", not me. I'm NOT an expert.
1) Burning 6.3 pounds of gasoline produces 20 pounds of carbon dioxide
Now...re-read again until it sinks in. To repeat: "Burning 6.3 pounds of gasoline produces 20 pounds of carbon dioxide"
2) Now...moving forward...a container...hanging from a scale...(note: a scale WEIGHS things).
3) Inside container is a gallon of gasoline.
4) you ignite that gasoline...doesn't matter by match, engine, doesn't matter.
5) the container is large enough and has enough atmospheric air in it to completely burn ALL of that gallon gasoline.
6) BEFORE ignition, scale reads 100 pounds.
7) AFTER ALL THAT GALLON OF GASOLINE HAS BURNED it NOW weighs 113.7 pounds.
8) we started with a CLOSED CONTAINER on a scale. Inside is gasoline, air, ignition source. Experts said I'll repeat once again "Burning 6.3 pounds of gasoline produces 20 pounds of carbon dioxide".
9) So 100 pounds, 6.3 of which is gasoline is now gone...turned into CO2 (and other gasses)...so 100-6.3=93.7 pounds + 20 pounds CO2=113.7 pounds.
10) Burning 6.3 pounds of gasoline produces 20 pounds of carbon dioxide, therefore AS IT BURNS we'll watch the scale increase.
PROVE ME WRONG.