Creating bubbles infused with “smoke” from dry ice is a captivating science demonstration. This visually striking effect transforms ordinary soap films into mesmerizing, billowing spheres. The process utilizes the unique properties of solid carbon dioxide to produce an impressive display. This guide details the steps to safely and effectively produce these fog-filled bubbles.
Essential Safety Precautions
Dry ice is solid carbon dioxide (CO2) and poses hazards due to its extremely low temperature of approximately -78.5°C (-109.3°F). Direct contact with bare skin can cause severe frostbite. Handling the material requires insulated gloves, such as thick leather gloves or oven mitts, or specialized tongs to avoid injury.
Dry ice rapidly converts directly from a solid to a gas, a process called sublimation, releasing significant volumes of CO2. Because carbon dioxide is heavier than the air we breathe, it tends to settle in low areas and can displace oxygen, leading to a risk of asphyxiation. Therefore, this experiment must always be conducted in a well-ventilated area, such as outdoors or near an open window.
Never store or seal dry ice in an airtight container, like a glass jar or sealed plastic bottle. The continuous buildup of gas pressure can cause the container to rupture violently, posing a serious projectile risk.
Gathering Your Materials
Preparing for the demonstration requires several simple items. Begin with a small amount of dry ice pellets or chips, sourced from specialty distributors or some grocery stores. You will also need a wide-mouthed container, such as a large bowl, pitcher, or beaker, to hold the solution and the dry ice.
The process requires warm water, which accelerates sublimation, and a quality bubble solution, which can be store-bought or mixed at home with dish soap and glycerin. Safety equipment includes thick gloves or tongs for handling the dry ice.
The Bubble-Making Process
The first step involves preparing the base solution within the wide-mouthed container. Pour warm tap water into the vessel, filling it approximately halfway, and then gently stir in a generous amount of bubble solution until the mixture is uniform. The warmth of the water is important because the heat energy transfers rapidly to the dry ice, speeding up the transformation.
Using protective gloves or tongs, carefully add several pieces of dry ice to the prepared soap and water mixture. Immediately, the dry ice will begin to sublimate, producing a dense, cloudy fog that spills over the edges of the container. This fog consists of CO2 gas mixed with condensed water vapor, which fills the resulting bubbles.
To create the large, dome-like bubble, form a soap film skin over the container opening. This is achieved by wetting a strip of cloth, a towel, or a gloved hand with the bubble solution. Slowly drag the wet cloth or hand across the rim, ensuring a thin, continuous layer of soap film stretches across the opening.
Once the film is secured, the CO2 gas and water vapor mixture rising from the sublimating ice pushes upward against the soap skin. The pressure differential causes the film to expand slowly into a large, billowing dome. Eventually, the pressure causes the bubble to detach from the rim or burst, releasing the heavy fog contained inside.
Understanding the Science
The demonstration relies on sublimation, the unique physical process where solid carbon dioxide (CO2) transitions directly into a gaseous state when it absorbs heat, rather than melting into a liquid. This phase change occurs rapidly when the solid CO2 reaches its sublimation point of -78.5°C (-109.3°F).
Adding dry ice to warm water significantly accelerates sublimation because the water provides a substantial source of thermal energy. The heat energy transfers to the solid CO2, causing it to quickly convert into gaseous CO2, which provides the pressure to inflate the soap film into a bubble.
The visible “smoke” is not the carbon dioxide itself, as CO2 gas is colorless and invisible. The dense fog arises because the extremely cold CO2 gas chills the surrounding air, causing water vapor to condense into tiny liquid water droplets. The soap solution then acts as a flexible membrane, trapping this mixture of invisible CO2 gas and visible water fog inside the bubble structure.