How much does 1 gallom of gas weigh?

Answer 1

Gas is typically measured in cubic feet or cubic meters at a particular temperature and pressure and will depend on the composition of the gas. So, as asked, there is no answer.

I have rephrased your question: What is the expected weight of natural gas at standard condition in a one US gallon container?

Answer: 0.00588 to 0.007487 pounds

Standard conditions are pressure = 14.7 psia and temperature = 60 degrees F. At these conditions, natural gas gravity = 0.7 to 0.9 kg/m3 at standard conditions, depending on composition. See first link. This is equal to 0.044 to 0.056 pounds per cubic feet. There are 7.48 gallons in a cubic foot, so:

0.044 pound/cubic feet *(1 cubic foot/7.48 gallons) = 0.00588 pounds

0.56 /7.48 = 0.007887 pounds

see links