Cold Pack Science

People have been trying to keep items cold throughout history and at one time, ice was the only method. If someone didn’t have access to ice, the only preservative that they could use for food was salt and in some countries, salt was worth more than gold. In some cultures, they would travel for hundreds of miles, with blocks of salt on the backs of camels so that they could sell the salt in the markets.

In the days before refrigerators there were vendors that would go through the streets bringing large blocks of ice to each house so that they could keep it in their ‘freezer’ to keep food preserved.

While today’s refrigerator takes the place of those vendors, we continued to look for ways to keep food cold when we weren’t at home. The invention of the ‘cold pack’ is a little piece of science wrapped up in a package with a bit of water added.

Cold packs actually use a scientific process called ‘endothermic reaction’. There are chemicals in one area and when they are added (or shaken) into the water it causes a reaction that makes the water icy cold. The reaction itself isn’t just turning something cold, it is actually absorbing the heat. Cold packs are great for camping, hiking, school lunches and are even used in the medical industry to keep certain medicines from spoiling.

There are many cold pack manufacturers and some use the same chemical mix, while others claim that their specific chemicals work better than the others. Some of the chemicals achieve really cold temperatures when they are mixed with water. The reaction can quickly take room temperature water down to freezing in ten to fifteen minutes.

Some chemicals that are added to water create a short term freezing and then slowly return to room temperature. Others can maintain the cold for longer periods of time, but eventually, they will also return to the outside temperature. The value of the cold pack itself is based on what you are going to need it for: a long time or a shorter time. But no matter what the use, a cold pack is easy to carry around and is so much better than the old fashion salt or ice block delivery methods.

Would you be interested in doing a science project to figure out what makes the best cold pack? Can you think of any other uses that would be beneficial for cold packs? Do you have any recommendations to change how manufacturers make cold packs?