i was told that every gallon of gas you burn produces a gallon of water is there any truth to this

I don't see how it could give a 1:1 ratio. Water is not the only by product coming from combustion. CO2 as well as other additives in gasoline are also given off.

perhaps it has something to do with the combustion of the air humidity as a net product of chemicals at the tailpipe....

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

I wouldn't be surprized -- look at all the steam you can see coming from the tailpipe on a winter's morning.

It'd be a good puzzle for a high school chem student.

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95 E320 Cabriolet, 169K

I don't think it produces water. But I believe it probobly condenses that much, at least at start up.

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Thank You!
Fred
2009 ML350
2004 SL600
2004 SL500
1996 SL600
2002 SLK32
2005 CLK320 cabrio
2003 ML350
1997 C280 Sport

you forget the stoichometric ratio.
while you may have burned a gallon of gas, you have also consumed ~15 gallons of air.

its possible.

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'O=00=O'
bmw 2002.
long live the legend

We went over that in chemistry in high school. If perfect combustion then it would give a gallon of water and the equasion balances with carbon dioxide with gasoline combustion. Gasoline is C8H22, the carbon bonds to oxygen to form carbon dioxide and the hydrogen also bonds to oxygen to form water. But combustion isn't perfect and you get unburnt hydrocarbons, carbon monoxide and other various NOx. Plus a signifigant amount of water.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

15:1 by weight, not by volume. That's LOTS more "gallons" of air.

And "water" in this case means H2O molecules, be they gas, vapor or liquid.

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Norm in NJ
Next oil change at 230,000miles