In a captivating experiment with liquid nitrogen, its temperature of -196 °C is used to demonstrate intriguing effects on balloons. When liquid nitrogen is poured over an inflated balloon, it causes the gas inside to cool down, reducing the balloon's volume and leaving behind a thin, skin-like object. Upon warming, the balloon regains its original shape and volume. The spectacle intensifies with a helium-filled balloon, initially tethered but attempting to rise due to helium's natural buoyancy. However, when cooled by liquid nitrogen, the helium balloon shrinks, sinking on the table. Upon reheating, the balloon rises and floats once more.

Two explanations are offered: First, the volume of the balloon decreases due to low temperature, making the helium balloon denser than air and causing it to sink. Second, the pressure of the gas inside the balloon tends to decrease at low temperatures. Atmospheric pressure forces the balloon to a smaller volume until pressures inside and outside equalize. Air can be compressed more than helium at these temperatures, as helium remains a gas. Upon reheating, the pressure rises, and the balloon expands to its original shape.

The helium-filled balloon rises in the air due to its lower average density compared to the surrounding air. Conversely, when cooled, the balloon's volume increases, elevating its average density and causing it to descend. This experiment vividly illustrates the impact of temperature on gas volume and density, creating a captivating display of scientific principles.