what is the difference in weight (in pounds) 100 gallons of water is 8.34 pounds per gallon and 100 gallons of gasoline at 0.71 kilograms per liter?
100gal * 8.34lb/gal = 834 lb
100gal * 0.71kg/L * 2.2lb/kg * 3.78L/gal = 590 lb
or, note that 1kg/L = 8.34lb/gal