Sodium acetate trihydrate, also known as sodium ethanoate or simply sodium acetate, is the sodium salt of acetic acid. You can make it by heating baking soda and white vinegar until most of the liquid has evaporated. When permitted to cool on a paper filter to absorb excess moisture, a raw form of sodium acetate trihydrate is left behind. This is the first step in making a product known as hot ice, which is just one of the uses for sodium acetate trihydrate.
Hot Ice
The term "hot ice" sounds like an oxymoron, but it's actually an accurate description for the instant liquid-turned-ice substance that forms when sodium acetate trihydrate is heated and subsequently cooled. When this sodium salt is completely dissolved in simmering water and then removed from the heat, the liquid becomes supersaturated and cools to room temperature without crystallizing. Blow across the gel-like substance, though, or touch it with your finger, and an exothermic reaction occurs. This means that heat is released and ice-like crystals instantly form without the need to reach freezing temperature.
While this is a fun and interesting experiment carried out in many high school and college science labs, hot ice has real world applications. According to instructors at the University of Washington's Department of Atmospheric Sciences, molecules transforming from a liquid state to a less excited solid state create surplus of energy that is released into the surrounding environment as an example of latent heat. Since the chemical reaction generates heat upon crystallizing, hot ice is used to warm things up, such as hand warmers, heating pads and baby bottle warmers.
Food Industry
Sodium acetate trihydrate is used in the food industry as a flavoring and seasoning agent. It is sometimes used in combination with acetic acid to form sodium diacetate, which imparts the flavor of vinegar. In fact, this substance is a common flavoring ingredient in many brands of salt and vinegar potato chips. It is also used to season sauces, ketchup and bread crumbs used in the preparation of fast food chicken and fish. This substance is also used to enhance the flavor of meat and poultry, as well as to control bacteria in processed meats and deter mold in bread dough.
Industrial Uses
Sodium acetate is used in optical lithography and photoengraving as a light sensitive "photoresist" agent to transfer patterns from plates so that the same design may be engraved on the target material lying below. It is used to regulate the curing or hardening properties of chemicals used to produce synthetic rubber. Sodium acetate is also combined with chromium sulfate and used to tan animal skin, a process known as mineral tanning or chrome tanning.
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