What is inside disposable hand warmers?

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The U.S. team made history at the International Chemistry Olympiad.

Hand warmers can mean the difference between playing outside for as long as possible and calling it a day early.The little disposable pouch that emits warmth within seconds of being exposed to air is something that anyone who braves cold temperatures might be tempted to try.

Keiko Ishikawa, a marketing manager at Mycoal USA, said that hand warmers date back centuries to when people in Japan would use hot stones to warm their hands.She says portable hand warmers filled with hot ash followed.You can buy a variety of hand warmers based on battery packs and lighter fuel, but disposable ones rely on chemistry.

It is possible to turn up the heat in your mittens by using disposable hand warmers.The pouch usually contains iron powder, salt, water, an absorbent material, and activated carbon.Oxygen can be seen when the pouch is removed from its packaging.Oxygen reacts with the iron powder located inside to form iron oxide and release heat.

The absorbent material can be made from wood, polyacrylate, or vermiculite.It helps retain the water.The heat can average 135 F with the help of the activated carbon.

The chemistry of disposable hand warmers is simple.Joe Vergona, manager of engineering and product development at Grabber Performance Group, says, "You want to make this thing act quickly because people like to open up the packet and feel warm right away, but you also want it to last a long time."Some hand warmers last seven hours, while others can last more than 24 hours.

Some companies increase the amount of iron in the packet in order to prolong the life of a hand warmer.

It is possible to experiment with iron powder.Vergona says that you can change how quickly the reaction happens or how much of the warmer is reacted at one time.He says that the surface area of the iron can react with oxygen to produce heat.

The performance of the hand warmers is affected by the pouch material.There is a balance of ingredients inside the pack and the performance characteristics of the pouch.The iron powder and other ingredients are contained in a blended nonwoven material.The reaction occurs more quickly if the pouch admits more oxygen.Toe warmers use a nonwoven material that lets in more oxygen to compensate for the low-oxygen environment inside a shoe.Vergona says that the size of the holes will affect how much oxygen enters the warmer.

To extend the shelf life of hand warmers, the outside wrapper is specially chosen to ensure that minimal amounts of oxygen get in and minimal water gets out.Oxygen can get in and ruin the product, so old plastic and hand warmers will last a week and die.The wrappers are usually made of plastic.

The chemicals used to produce the heat-releasing reaction are the main difference between disposable hand warmers and some reuse versions.Reusable hand warmers don't contain iron but instead use a supersaturated solution of sodium acetate that releases heat.The solution is restored to its supersaturated state when the packet is boiled.Hand warmers can't be used again.

Hand warmers can keep humans from getting too cold.Tropical fish can survive transportation through chilly climates if Grabber sells heavy-duty warmers.