Invisible Water Video and Instant Ice Explained

There are a number of videos circulating around the web that offer practical demonstrations of scientific principles in a fun way. Everybody remembers the Mentos/Diet Coke videos from last year, but that is only one such example. Invisible water is the latest to gain popularity. Of course, there's no such thing as invisible water, but the video clearly shows a boat floating in a glass tub of invisible water and then sinking slowly when what would seem to be invisible water is bailed into it. How can this be? Watch the invisible water video here and then come back for the explanation.

What is Invisible Water?

Invisible Water is really just a very dense gas. In this case, sulfur hexafluoride is used. We've all seen a helium balloon rise into the air. It rises because helium weighs less than the same volume of air. Invisible water is simply the opposite, a gas that weighs more than air. When it is carefully pumped into the glass tub, its weight keeps it from mixing with the air. So it stays inside the walls, held down by its own weight. When the hollow boat is placed on the invisible water, it displaces enough of the invisible water to compensate for the weight of the boat, exactly like a boat in real water. Filling the boat up with sulfur hexafluoride or invisible water adds weight to the boat, just as adding real water to a real boat would. When the combined weight of the boat plus invisible water inside it is higher than the weight of invisible water alone, it sinks. This is a great way to teach the scientific principles of density and buoyancy. Invisible water is another one of those things that looks like magic, but is really just good old science.

Not Invisible water, but Instant Ice

This next one involves real water, not Invisible Water. In this case, an ordinary bottle of water will be tapped against the ground and will freeze solid in a matter of seconds. Watch it here then come back for the explanation. Instant Ice is created when water is cooled to well below its freezing point of 32 degrees Fahrenheit without allowed to freeze. Pure water if it is kept still won't freeze at 32 degrees. For ice to form it needs a catalyst or something to start the first crystal around. This catalyst can be an impurity in the water, a tiny air bubble, or a piece of ice. In the case of the bottled water, as long as it is left undisturbed, it can be cooled to much less than 32 degrees without freezing. Bumping the bottle causes tiny air bubbles to form. Once the bubbles are present, they act as the catalyst for the crystallization of freezing to begin. From that point the ice itself catalyzes the rest of the water to switch over to ice.