FACT NEXUS on Instagram: "The gas that is known for being very heavy and visibly flows and settles like an "invisible water" in scientific demonstrations is sulfur hexafluoride (SF6). • Density:SF6 has a density of approximately 6.17 grams per liter at standard conditions, making it over five times denser than air (air is about 1.225 g/L). This high density relative to air is what allows it to be "poured" and hold objects like a small foil boat or an air-filled balloon, much like water supports