A liter is the metric unit of volume, not of mass or weight. The weight of a substance occupying 1 liter depends entirely on its density. For example, water has a density of approximately 1 gram per milliliter; hence, 1 liter of water weighs about 1 kilogram, or 2.2 lbs.
Metals are generally far more dense than water. Gold has a density of 19.3 grams per milliliter (or cubic centimeter), according to Elmhurst College. One liter of gold contains 19,300 grams (or 19.3 kilograms) of this element. Consequently, a liter of gold weighs almost 20 times more than a liter of water.