An instant ice pack is a plastic bag filled with frozen gel that is capable of maintaining extremely low temperatures for an extended period of time.
Cold Packs and Endothermic Reactions
Unlike traditional ice packs, instant ice packs do not need to be stored in a freezer before use and can freeze instantly through a chemical reaction.
Instant ice packs are used therapeutically and are useful in emergency situations since they can be transported at room temperature. Many people also use instant ice packs in coolers to preserve meat, dairy products and other types of food. Instant ice packs use an endothermic reaction between water and ammonium nitrate to achieve cool temperatures rapidly.
An endothermic reaction occurs when two separate compounds interact to absorb energy in the form of heat. Before it is used, an instant ice pack contains both water and ammonium nitrate in separate tubes.
When these tubes are broken, the water and ammonium nitrate mix, setting off an endothermic reaction and causing the water to freeze. The freezing of the water prevents all of the ammonium nitrate from instantaneously mixing with the water. As the ice melts, the water mixes with additional ammonium nitrate, causing additional endothermic reactions and forcing the melted ice to re-freeze. This process allows instant ice packs to remain frozen and maintain extremely low temperatures for an extended period despite being stored or used at room temperature.
Instant ice packs are extremely useful for preserving food, particularly in situations where it is not possible to refrigerate food for long periods. Unlike pure ice, the water from instant ice packs cannot mix with food. Instant ice packs are also significantly more powerful that pure ice: four ice packs, when stored with food in a cooler, provide the same chilling power as 10 to 20 pounds of ice. Instant ice packs are also used extensively by medical professionals in both emergency and non-emergency situations.
Cold temperatures cause muscles to numb and constrict, preventing the muscle from being overworked and allowing it to heal. Instant ice packs are smaller and much easier to transport than pure ice, making ice packs a favorite tool of physical therapists. Instant ice packs are also reusable, which makes them more cost effective than pure ice. Contributing Writer updated on August 30, Pin Share Tweet Share Email.
How Refrigerators Work
Overview of Instant Ice Packs. How Instant Ice Packs Work. Uses for Instant Ice Packs. Show Comments.This science project explores endothermic reactions by comparing the temperature change that results from various chemicals added to water. Did you ever wonder what is inside of a cold pack? You can make a basic cold pack by mixing a salt such as potassium chloride or soda such as baking soda with water.
Mixing the two creates a chemical reaction that uses up energy, which makes the mixture colder. You can see which substance cools off water the most by trying out this experiment. Add four teaspoons of sodium bicarbonate to the water and stir with the thermometer. Record the resulting temperature. Subtract the temperature from Step 2 from the temperature in Step 3. This will give you the change in temperature. Chemical Added. Original Temperature.
Final Temperature. Temperature Change. Repeat this process with the citric acid, potassium chloride, sodium carbonate, and calcium chloride.
Record all data. Analyze your data. Which of the substances would create the best cold pack? Bookmark this to easily find it later. Then send your curated collection to your children, or put together your own custom lesson plan.
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My Education.Energy is conserved in chemical reactions, so the total amount of energy in the universe at the end of a reaction is the same as it was before the reaction. When a chemical reaction happens, energy is transferred to or from the surroundings.
When energy is transferred to the surroundings, this is called an exothermic reaction, and the temperature of the surroundings increases. Examples of exothermic reactions include:. Everyday uses of exothermic reactions include self-heating cans and hand warmers. When energy is taken in from the surroundings, this is called an endothermic reaction and the temperature of the surroundings decreases. Examples of endothermic reactions include:.
Everyday uses of endothermic reactions include instant ice packs which can be used to treat sports injuries. The slideshow describes an exothermic reaction between dilute sodium hydroxide and hydrochloric acid and an endothermic reaction between sodium carbonate and ethanoic acid. Sodium hydroxide solution is poured into a beaker of hydrochloric acid which contains a thermometer showing room temperature.
The beaker now contains sodium chloride and water, and the thermometer is showing a rise in temperature, so the neutralisation reaction is exothermic. Sodium carbonate powder is tipped into a beaker of ethanoic acid which contains a thermometer showing room temperature. The beaker now contains sodium ethanoate, water and carbon dioxide, and the thermometer is showing a fall in temperature, so this was an endothermic reaction.
In en dothermic reactions, energy en ters. In ex othermic reactions, energy ex its. A study of the energy changes involved in chemical reactions, whether exothermic or endothermic. Reactions and temperature changes Energy is conserved in chemical reactions, so the total amount of energy in the universe at the end of a reaction is the same as it was before the reaction. Examples of exothermic reactions include: combustion reactions many oxidation reactions most neutralisation reactions Everyday uses of exothermic reactions include self-heating cans and hand warmers.
Examples of endothermic reactions include: thermal decomposition reactions the reaction of citric acid and sodium hydrogencarbonate Everyday uses of endothermic reactions include instant ice packs which can be used to treat sports injuries.Cold packs are usually plastic bags full of a dry salt with a breakable capsule containing water.
When you want it to turn cool, you break or rupture the capsule and the water mixes with the salt in an endothermic think that endo- means into and that the heat is going into the mixture and has to come out of the surroundings process. The salt often used is ammonium chloride since it gets quite cold when it dissolves.
These are mostly not reusable, since to reactivate them you would have to dry the ammonium chloride out. There are a couple of kinds of hot packs. One that is reusable is a plastic bag that contains a supersaturated solution of something like sodium acetate. A supersaturated solution contains more of the solute dissolved solid than it theoretically can at a certain temperature usually room temperature.
The crystallization of the solute is triggered by something like flexing a coin shaped piece of metal which has a slit in it and creates a disturbance that causes the crystallization. As the material crystalizes it heats up in an exothermic think exo- out of, the heat comes out of the system into the surroundings process.
You can throw the plastic bag into some boiling water until it goes back into solution. Just let it sit until you are ready to use it again. You can buy these kind of things at sporting goods stores because they are used on injuries or to keep your hands warm while you are skiing.
There is another heating thing that I don't know too much about that gets really hot. I think it is used to heat up the military ready-to-eat meals. I think it is a mixture of NaCl, Fe powder, salt and some water.
The iron forms rust so fast, the mixture heats up quite a bit. This one is non-reusable also. Chemicals can store energy and release it in the form of heat. A chemical reaction that releases heat is called an exothermic reaction.
But chemical reactions can also absorb heat from the environment and get cold. These reactions are called endothermic reactions. When chemicals are dissolved in water, sometimes heat is released, and sometimes heat is absorbed. Heat is given off as a result of a chemical reaction. They are constructed of a large pouch containing a dry chemical plus an inner pouch of water.
This action mixes the water with the chemical starting the exothermic or endothermic reaction. If the dissolving of the chemical in water is an endothermic process and absorbs heat energy, it is a good candidate for making a cold pack because this process will lower the temperature of the content of the pack.
If the dissolving of the chemical in water is an exothermic process and releases heat energy, it is a good candidate for making a hot pack because this process will raise the temperature of the content of the pack. My best guess would be that cold packs rely on an endothermic reaction that absorbs energy from the surroudings. Hot packs probably rely on an exothermic reaction that releases energy into the surroundings.
If you're just talking about an ice cold pack, then the melting of the ice is an endothermic process that requires energy and therefore feels "cold" to the surroundings. Just as a little side note the way something "feels" doesn't necessarily tell you its temperature.If you use larger beakers, you will need to make sure you use enough water to immerse the thermometer bulb, and increase the amounts of the other reactants proportionally so you maintain the same concentrations.
Temperature, chemical reactions, endothermic reactions, exothermic reactions. Next: Materials. Next: Teacher Prep.
Next: Lesson. Next: Reviews. Science Buddies. Was this review helpful? Report Inappropriate Comment. Be the first one to review this lesson plan. Grade Range. Learning Objectives. Define the criteria and constraints of an engineering problem designing an instant cold pack Identify the chemical reaction that best meets the criteria and constraints.
Student worksheet PDF. Leave a Review. Explore Our Science Videos. Overview How do "instant" cold packs get cold when they are stored at room temperature, unlike a regular ice pack which must be stored in the freezer? In this lesson plan, students will explore several endothermic and exothermic reactions, and use their observations to choose the chemical reaction that best fits the design constraints for their own chemical cold pack.
Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.
The Cold Pack: A Chilly Example of an Endothermic Reaction
Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions. Analyzing and Interpreting Data. Analyze data to define an optimal operational range for a proposed object, tool, process, or system that best meets criteria for success.
A : Structure and Properties of Matter. Some chemical reactions release energy, others store energy.Educational Resources. Has this ever happened to you or someone you know? Your teacher grabs the first aid kit and pulls out an instant cold pack. The teacher presses it to your ankle. It feels cold! An instant cold pack is a plastic package filled with chemicals.
When you crunch the cold pack it becomes really cold, really fast. What is happening? How can the chemicals mix and make such a chilly reaction so quickly? The answer can be found in thermodynamics! This is a branch of science that explores the transfer of energy. In thermodynamics, chemical reactions can be classified as endothermic or exothermic. Exothermic reactions are reactions that give off energy in the form of heat.
For example, a fire is one type of exothermic reaction. A fire gives off heat when you burn a fuel source - like wood - in the presence of oxygen. Endothermic reactions are the opposite of exothermic reactions. They take in heat energy from their surroundings.
This means that the surroundings of endothermic reactions are colder at the end of the reaction. In chemical reactions like the ones in your cold packthe bonds between molecules in the reactants original chemicals are broken. New bonds are made in the products what you have left after the reaction happens. Breaking bonds takes energy, and forming bonds releases energy. If more energy is needed to break bonds than is released when the new bonds are formed, you have an endothermic reaction.
An instant cold pack is the perfect example of an endothermic reaction. There are many possible ingredients in an instant cold pack, but they often contain ammonium nitrate and water.
The ammonium nitrate is stored in a sealed plastic bag that is surrounded by water. When you pop the plastic that contains the ammonium nitrate solid, it comes into contact with water and dissolves. The chemical reaction between ammonium nitrate and water is an endothermic reaction. The reaction needs more energy than it produces, so it pulls in heat energy from its surroundings and the bag gets cold.
The chemical reaction describing what happens when ammonium nitrate is dissolved in water can be represented as:. Measuring the temperature change is the easiest way. Scientists measure the temperature of a reaction before and after it is completed. If the reaction takes place in a solution, then scientists measure the temperature of the solution before and after the reaction. This makes it an exothermic reaction.
If the temperature decreased after a reaction, then it absorbed energy. This makes it an endothermic reaction. The other way to determine if a reaction is exothermic or endothermic is to calculate the change in internal energy. This internal energy is called enthalpy of the reaction. This value can tell us if the reaction is exothermic or endothermic.Introduction Endothermic reactions are accompanied by the absorption of heat.
The dissolving of ammonium nitrate in water is an example of an endothermic reaction. The solution resulting from this mixture is colder than either the ammonium nitrate or the water. This is the simple explanation of what happens in an instant ice pack.
The more detailed information will be discussed in the following paragraphs. Cold Packs Most cold packs come with a fabric cover made to absorb condensation and to protect the skin from contacting the surface of the cold pack.
Cold packs are used for injury or muscle relief. The cold pack contains two bags one containing water and the other containing ammonium chloride. Once the ammonium chloride is broken it reacts with water causing a endothermic reaction.
Cold packs remain cold for different lengths of time through the reaction extending up to fifth teen minutes precession, giving users relief from inflammation and pain at the site of injury. Many cold packs are reusable, by refreezing the e pack. Once the pack is refrozen it contains stability in the reaction. It can then be reapplied to the injury causing an endothermic reaction giving comfort to the surrounding area.
Cold Pack Reactions Cold packs have a endothermic reaction that usually contains water and a packet of ammonium chloride. The Cold pack is activated by breaking the barrier separating the water and ammonium allowing the chemicals to mix. Once the cold pack is placed to the skin, energy is released keeping the cold pack reacting for a period of time.
Endothermic reaction absorbs heat causing the cold pack to keep reacting until the cool of the pack is warm up to the surrounding area. Endothermic reaction is the opposite of exothermic reaction absorbing the surrounding heat. When the ammonium chloride reacts with water it has a chemical reaction that will give off a cold effect, when soaking up heat from the body.
How Cold Packs Work The cold packs have two bags, a strong outer plastic bag with a thin plastic bag inside. When the inner bag is squeezed the bag ruptures, and the water it contains mixes with the ammonium nitrate and the endothermic reaction occurs.
This cooling reaction occurs instantaneously but lasts for about an hour. How does this reaction sustain itself for twenty minutes? This question will be answered later in this explanation.
The type of cold pack presented here contains ammonium nitrate, which is a white crystalline substance. When these crystals react with water they split into positive ammonium ions and negative nitrate ions. Due to the energy expended by the water in order to dissolve these crystals, the water becomes colder.
The salt family of chemicals contains ions, which are particles with electrical charges. Due to the fact that opposite polarity ions attract each other, they form a solid crystal that is called salt.