Chemistry Experiments - Colour Changing by Dry Ice

Dry ice is a fascinating substance which, when handled right, can be the basis for a host of simple experiments. We list many further examples on our web site. But where do you get it from? Big supermarket chains cool their fruit with dry ice. If they are in use, you can see the tubes emitting a cold mist. If you ask at one of these supermarkets, most will let you have some dry ice from their stores. Some supermarkets even offer a free dry ice cooling service when you purchase frozen goods.The dry ice, solid at a temperature of -78° Celsius, evaporates in the much warmer water. Dry ice has the characteristic if changing from a solid state directly to gas. Water can dissolve large amounts of Carbon Dioxide. When saturation is sufficient, a small proportion will react as follows:

H2O + CO2 -> H2CO3

The Oxonium ions cause the indicators to change colour. As we did add some alkaline solution, it is more correct to say that this is neutralised first by the Carbonic acid which leads to the formation of small amounts of Carbonate und Hydrogen Carbonate.

The soap solution in the first beaker starts to foam as the Carbon Dioxide is released.

The white mist is the result of cooling the air, condensing the moisture in the air above the beakers. When using warm water, this is proportionately more intense.
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