What Are Chemical Cold Packs? Curious Kids Should Know How It Works! | Kidadl

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What Are Chemical Cold Packs? Curious Kids Should Know How It Works!

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If you have ever suffered from a bruise or a bump, you must have experienced someone asking you to put ice or a cold pack on it.

If you open any first aid kit in your house, you will find a hot or cold pack in it. Hot and cold packs are the very first method of helping in muscle pain.

In 1805, Frederic Tudor realized how helpful ice could be to people in warmer regions. He then started sailing big chunks of ice from colder regions to hotter areas. This was a very profitable business for him. Even after his death, people followed this business model and sold ice.

John Gorrie, in 1890 was granted the first U.S. patent for mechanical refrigeration. This led to an evolution in ice manufacturing, and artificial ice plants began to be created. These innovations ultimately led to the production of instant cold packs. Now, instant cold packs are found all over the world. Read on to learn more about them.

Why not check out some other articles, too, like, do gas stations cause soil pollution and do glow sticks have glass in them!

Chemical Cold Packs: Meaning

Chemical cold packs are bags filled with liquid that instantly become cold on hitting or shaking it. The liquid inside those bags is water; inside the water is another inner bag or tube containing ammonium nitrate.

When this ammonium nitrate mixes with water, it creates a reaction known as an endothermic reaction. Endothermic reactions are chemical reactions in which heat energy is absorbed, causing the cold pack to become cold instantly. The temperature of the solution inside the cold pack falls to 35 F (1.7 C). A chemical cold pack usually lasts for 15-20 minutes. Interestingly, unlike hot packs having an exothermic reaction, the chemicals in this pack undergo an endothermic reaction.

What are chemical cold packs made of?

Instant cold packs are typically made of a chemical reactor and water. The most common chemicals used in chemical cold packs are ammonium chloride, ammonium nitrate, urea, and calcium ammonium nitrate.

Ammonium Chloride: This chemical reactor reacts with water to give a cold sensation. It is an ionic compound. When ammonium chloride is dissolved in the water, it forms an aqueous solution and splits into positive ammonium ions and negative chloride ions. For this split, energy is required. This energy comes from heat. A temperature change happens within the solution. Swallowing this chemical can create severe injury to the gastrointestinal tract.

Ammonium Nitrate: Ammonium nitrate is commonly found in ice packs. It is a white, crystalline substance. It breaks up into positive and negative ions in its reaction to water. The ammonium ions are positive, and the nitrate ions are negative. The water molecules give up some of their stored energy to dissolve this substance. This results in the cooling down of water due to heat loss. Ammonium nitrate's reaction with water is the most common example of endothermic reactions.

Ammonium nitrate is very dangerous if swallowed. It causes dilation of blood vessels. This can cause the flow of blood to body organs to reduce and lower blood pressure. This can cause serious health effects like losing the oxygen-carrying ability of red blood cells, methemoglobinemia, and destruction of red blood cells, hemolysis.

Urea: Unlike the previous two reactors, this is not very toxic as a reactor. Urea is difficult to dissolve as the concentration increases, and urea dissolves in its own weight in water. To dissolve the urea, the temperature falls, making it an endothermic reaction. But if swallowed in sufficient quantity, it may cause adverse effects such as nausea, drowsiness, vomiting, confusion, and dizziness.

Calcium Ammonium Nitrate: Calcium ammonium nitrate is a mixture of calcium carbonate and ammonium nitrate. Calcium carbonate is nontoxic, but still, the presence of ammonium nitrate makes this a dangerous solution if swallowed.

You cannot reuse a single-use ice pack because once the reactions are complete and the chemicals inside have reacted with each other, they cannot be refrozen and reused.

Reusable ice packs are available; they must be frozen in refrigerators to bring down their temperature after use. If they are left stored at room temperature, they cannot lose heat energy on their own. Reusable ice packs have different chemistry behind them. Ice packs contain various types of materials that keep them cold, flexible, and reusable. These materials vary with the kind of ice pack and manufacturing methods. Some commonly used substances are hydroxyethylcellulose, propylene glycol, water, colored dye, and vinyl-coated silica gel.

Propylene glycol is a synthetic liquid used to lower the freezing temperature. It is absorbent and keeps the ice pack flexible at all temperatures.

Hydroxyethylcellulose is used as a thickening agent in instant cold packs. Its other uses include acting as a thickening agent for shampoo and shower gels.

Water keeps the mixture inside the ice packs cold and flexible. Reusable ice packs contain distilled water. If we need to keep something cool, water is super helpful as it has a high latent heat of fusion and can absorb a lot of heat or warmth before they are warm-up at 32 F (0 C). The specific heat capacity of water is 4184 joules (J).

Silica gel is used to keep the mixture bound together and keep the temperature of the ice pack lower for a more extended period of time.

Colored dye is used for aesthetic reasons. Typically blue dye is used.

Did you know that Albert A. Robbins patented his instant cold pack way back in 1959? It was created to keep food and drinks temporarily cold. The modern ice pack came into existence from this invention. Though this was made to keep foods and drinks cold for a short period of time, technological advancements have led to the development of the instant cold pack. Now, it is even used in shipping industries for shipping perishable goods.

Chemical Cold Packs: Uses

Chemical cold packs are used for medical purposes like minimizing swelling around minor bumps, reducing pain, muscle spasms and reducing bleeding into the tissue. In case of an ankle sprain, cold packs reduce swelling in the affected area, and the reduced swelling minimizes pain. They are very widely used in Orthopedics.

Instant ice packs are also kept in ambulances because they treat heat illness. Heat illness requires fast treatment. Cold packs are convenient and easily portable as they don't leak and don't require cold storage.

An ice pack helps keep foods like meat, eggs, dairy products fresh.

Instant ice packs are often used in shipping containers as freezers to help regulate temperatures while shipping such products. There are specific ice packs used for shipping purposes that can stay at a cold temperature for an extended period of time.

Chemical hot and cold packs are created by dissolving salts into the water. But, the difference between the two is that the chemical reaction is an exothermic reaction instead of an endothermic one. Exothermic reactions produce heat instead of consuming it. This is the primary mechanism behind the chemical hot pack. Hot packs use calcium chloride or magnesium sulfate as salts instead of ammonium nitrate or urea. The hot pack helps reduce pain from overused and strained muscles. Heat therapy helps in increasing blood flow to pained areas and causing muscles to relax.

It is also important to know when to use hot therapy and when to use cold therapy. The wrong method can worsen the pain and conditions of muscles. In case of any inflammatory injury, instant ice packs are recommended. The signs of inflammation are pain, redness, loss of function, warmth, and tenderness.

Hot therapy dilates the blood vessels, which cold therapy constricts, so if there is no inflammation and muscle relaxation is the goal, hot packs are the answer. Hot packs also help in chronic pains like menstrual pains and muscle cramps.

Chemical cold pack or instant ice pack facts talk about the chemicals in it and how it reacts on the skin.

What is the process for making a chemical cold pack?

An instant ice pack is an ideal example of an endothermic reaction, and to create a cold pack, we need to create an endothermic reaction. The most common ingredient used in a cold pack is ammonium nitrate and water. In this reaction, solid ammonium nitrate is the reactant. When this reactant, an ionic compound, is dissolved into water, it forms into an aqueous solution. The solution is split into positive ammonium ions and negative nitrate ions. To dissolve an ionic solution, energy is required. In this reaction, it is supplied from heat energy. This causes a temperature change that makes the ice pack turn cold.

An easy way to create instant cold packs at home is by using rubbing alcohol and water. In a plastic freezer bag, add rubbing alcohol and water in the ratio of 1:2. Here too, an endothermic reaction takes place. This can be used as easy homemade cold therapy if you don't have an ice pack available. While applying this pack directly to the skin, a cloth should be placed between the pack and the skin.

Here at Kidadl, we have carefully created many interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'What are chemical cold packs? Curious kids should know how it works!' then why not take a look at '37 shocking facts about ocean pollution and its effect on marine life,' or '19 red sweet potato nutrition facts that make them better food choices!'

Written By
Srija Chanda

<p>An aspiring media professional, Srija is currently pursuing her Master's degree in Mass Communication at St. Xavier's University, Kolkata, after completing her degree in journalism. With experience in PR and social media, she has also honed her leadership skills through her participation in a youth parliament. Srija's interests include devouring books, watching movies, and exploring new places through travel.</p>

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