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Sodium Acetate Heat Pack Buy

Ever wondered how sodium acetate heating pads and hand warmers work? Despite being an effective way to warm your hands or soothe your body aches, they are a live action science experiment and fun to use! Once activated they heat up in seconds and can last up to 2.5 hours depending upon the size and amount of liquid inside.

sodium acetate heat pack buy

The fun part of the sodium acetate heat packs lies in how quickly the transformation of the liquid takes place once the disc is flexed; in a matter of a few seconds you watch the clouding like crystallization take place and instantly feel the heat. At this stage it is recommended to gently knead the heat pad to evenly disperse the liquid and prepare for use.

This is exactly the phenomenon which is applied in the working of sodium acetate heat packs to produce heat. The special ingredient within these heating pads is sodium acetate. When it is mixed with water and a stainless steel disc you have the perfect solution for instant, safe and a reusable form of heat. When the disc of the heat pad is clicked, it pushes the liquid through the disc which immediately begins the process of changing the temperature of the liquid while keeping it in a liquid state. The temperature, as a result, rises up to 130 degrees Fahrenheit. The amount of liquid inside the heat pad determines the amount of time the heat pad remains hot until it eventually cools into a hardened state.

Is this safe? Yes, sodium acetate is the sodium salt of acetic acid. It's also the primary flavoring in many edible items such as potato chips and considered a food grade product and can be a common additive. It has a distinct vinegar like smell and completely safe when used in our heating pads.

Our sodium acetate heat packs are non-toxic and can stay warm for up to 2.5 hours and when they cool you can simply boil again. So, if have spent time inside a hockey arena, skiing, at a football game or waiting for public transit and felt your hands freeze, our hand warmers would have come in quite handy. For body aches, our heating pads provide the perfect temperature to soothe and provide relief.

A heat pack like the one you are describing contains sodium acetate and water. It turns out that sodium acetate is very good at supercooling. It "freezes" at 130 degrees F (54 degrees C), but it is happy to exist as a liquid at a much lower temperature and is extremely stable. Clicking the disk, however, has the ability to force a few molecules to flip to the solid state, and the rest of the liquid then rushes to solidify as well. The temperature of the solidifying liquid jumps up to 130 degrees F in the process.

When you boil the solid, you melt it back to the liquid state. You have to completely melt every crystal, by the way, or the liquid will quickly re-solidify. You can repeat this cycle forever, theoretically, just as you can freeze and melt water as many times as you like. The plastic pouch eventually wears out and leaks, though (since sodium acetate is a food additive, it is non-toxic).

Description: This phenomenon uses a supersaturated solution of sodium acetate. Clicking the metal disc releases a small number of crystals of sodium acetate which act as nucleation sites for the crystallization of the sodium acetate into a hydrated salt. Energy is released from the crystal lattice. The heating pack can be placed in boiling water and the sodium acetate can be dissolved again. This phenomenon shows how bond energy can be released. It also shows the importance of chemical engineering and could lead to a section where students design a device (or application) of their own.

I have a pocket warmer heat pack, which is basically a plastic pouch containing a solution of sodium acetate and a flexible metal disk. When the solution is melted and super-cooled it doesn't crystalize until the metal disk is clicked.

The claim made in the paper is that the metal disk is designed to trap tiny crystals between sheets of the metal, and these crystals do not melt when the pack is heated. When the metal is flexed these crystals are exposed and act as nuclei for crystallisation of the supercooled melt.

The same goes to the sodium acetate solution in the heat pack. The sodium acetate solution has a freezing/melting point of $55^o$C to $60^o$C, well above room temperature. However, it remains in liquid form, as it is apparently very stable. Clicking the metal disk however, causes some molecules to transform into a solid state, and this starts of a chain reaction to crystallize the sodium acetate solution. This is because it froms a nucleation centre, which crystallizes a few molecules of sodium acetate, and this/these will be the point of origination where the crystallization propagates. This then causes the temperature to jump to about $60^o$C(melting point of sodium acetate solution) to heat up. However, the heat pack has to be a "clean environment" for this to work. That is why even a tiny hole can cause it to crystallize without pressing the metal disk, rendering it useless.

Disposable chemical pads employ a one-time exothermic chemical reaction. One type, frequently used for hand warmers, is triggered by unwrapping an air-tight packet containing slightly moist iron powder and salt or catalysts which rusts over a period of hours after being exposed to oxygen in the air. Another type contains separate compartments within the pad; when the user squeezes the pad, a barrier ruptures and the compartments mix, producing heat such as the enthalpy change of solution of calcium chloride dissolving.

The most common reusable heat pads contain a supersaturated solution of sodium acetate in water. Crystallization is triggered by flexing a small flat disc of notched ferrous metal embedded in the liquid. Pressing the disc releases very tiny adhered crystals of sodium acetate[1] into the solution which then act as nucleation sites for the crystallization of the sodium acetate into the hydrated salt (sodium acetate trihydrate, CH3COONa3H2O). Because the liquid is supersaturated, this causes the solution to begin to crystallize over a few seconds, typically by propagating from the initial nucleation site and eventually causing the entire contained liquid to solidify, thereby releasing the thermal energy of the crystal lattice. The use of the metal disc was invented in 1978.[2]

Heating packs can also be made by filling a container with a material that has a high specific heat capacity, which then gradually releases the heat over time. A hot water bottle is the most familiar example of this type of heating pad.

Schematic representation for use of sodium acetate trihydrate PCM in (a) reusable PCM heat pack, (b) PCM hot vest, (c) PCM floor heating for buildings and (d) seasonal solar thermal energy storage and building heating.

When Sodium Acetate Trihydrate crystals are heated to the point of melting and then they are allowed to cool, the resulting solution becomes supersaturated. This solution is capable of cooling to room temperature without forming crystals. When clicking on a metal disc in the crystal solution, a nucleation center is formed which causes the solution to crystallize into solid Sodium Acetate Trihydrate again thus giving off heat. Unlike some other types of heat packs, sodium acetate heat packs can be easily recharged by boiling until all crystals are dissolved again.

Heat packs that contain supersaturated sodium acetate: These are reusable, the packs are boiled to dissolve sodium acetate. Inside is a metal clicker, once the pack cools to room temperature, crystallization of sodium acetate (an exothermic process) is triggered by the clicker, which gives the sodium acetate a nucleation point.

For an easy hand warmer, just pour sodium acetate into a resealable bag and add a crystal to activate it. To reuse, suspend the bag in boiling water until the sodium acetate reliquefies, then let it cool. When you want it to warm up again, add another crystal.

Where the paper tab left a gap, insert the funnel and fill the pouch with liquid sodium acetate, an alligator clip, and a solid crystal. Seal the hole in the vinyl with a hot iron, using parchment paper to prevent direct contact. Pinch the clip to set the trigger, then re-liquefy the sodium acetate.

This article was written with the intention to focus on middle school science experiments, however, I would not be surprised if high school teachers of physics and chemistry also benefit from it. How many calories of heat are in a hand warmer or "heat pack?"The heat pack is a convenient way to warm up your hands, but it also can provide a good lesson in physical science. It works by giving off heat in an exothermic physical change. The process is called "Fusion" which is whenever a liquid becomes a solid. In this case, "crystallization" is the specific form of fusion because crystals are formed. In order to melt these crystals, like melting ice, heat would have to be introduced and absorbed (endothermic). However, in this case, in order to form crystals, the reverse happens, heat is released (exothermic). Similarly, water has to have heat removed from it to form ice. Freezing is an exothermic process. But how much heat does it give off?The "Burn a Peanut Lab" is a well-known approach to measuring calories. The peanut is shelled, skinned, and skewered on a paperclip. It is then burned under a measured mass of water, for example, 200g. A thin metal container, such as a soda can, works fairly well. The temperature is measured both before and after and from these data you can determine the calorie content.

A safer experiment, or a follow-up experiment, is to measure the calories in a heat pack. You do not necessarily have to tell the students the instructions. They can try to figure out a process on their own. The way I usually do this experiment is to place one in an insulating container, with about 200g of water, and click the button. The water will begin to warm up. Don't forget that 1g is 1mL for water. 041b061a72


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