Understanding How Sodium Acetate Works as a Heating Agent

Hand warmers seem to work like magic, but science often appears astounding to many people. Industrial chemical supplier Bell Chem pulls back the curtain on this particular feat to reveal the magic at work is a chemical reaction. Read below on the wonders of sodium acetate and how it can almost spontaneously heat.

Sodium acetate is the sodium salt of acetic acid. When it dissolves in water, the sodium ions and acetate ions dissociate. This reaction is the basis of how heating pads and hand warmers work. To better understand the process, let’s think about something we should all be familiar with: water.

Imagine a glass of water in the freezer. As the water begins to freeze, it does not all freeze simultaneously. Instead, certain areas freeze, then the water in contact with those points likewise freezes until the contents of the glass are completely frozen – one chunk of ice – and the temperature, which has hovered at 32° F or 0° C while the water was busy transforming to ice, begins its descent to the temperature within the freezer. 

Now imagine if water had a different freezing point, where it became a solid at a higher temperature rather than a lower one. That is how sodium acetate, the starring ingredient in hot packs and heating pads, works. 

Sodium acetate can supercool rapidly when given a signal. The signal within a heat pack is generally a metal disk that, when twisted or clicked, forces a few of the sodium acetate molecules to crystallize into a solid state. These molecules cause a chain reaction to the adjoining molecules, which give off heat in the process. This heat can reach 130° F (54° C) very quickly. This is a stable process that eventually will lose some of its energy. Changing a heat pack back to its original temperature is simple: pop the heat pack into boiling water and the molecules move farther apart, transforming from a solid to a liquid state.

As with water, heat packs can be reheated endlessly since the chemical reaction will occur every time. However, the housing around the sodium acetate will eventually wear out, causing tears and holes in the plastic. If this does occur, the chemical sodium acetate, although it seems extreme, is completely nontoxic.

Bell Chem is your industrial chemical supplier based in Longwood, FL (just north of Orlando) with hundreds of products stocked in their 50,000+ square-foot warehouse, including sodium acetate. You can expect the highest quality products, expedited shipping options for maximum efficiency, and unrivaled personalized customer service. Let our knowledgeable and friendly customer service representatives and accounting staff personalize all your needs by either calling 407-339-BELL (2355) or by sending us an online message.