Environmental Chemistry

What is an exothermic reaction?

Exothermic reaction examples?

Examples of exothermic reactions - Demonstrations to try

Exothermic reaction and some examples are as follows :

An exothermic reaction is a chemical reaction that releases heat and has a negative enthalpy (-ΔH) and a positive entropy (+ ΔS). These reactions are energetically favorable and often happen spontaneously, but sometimes you need a little extra energy.

Exothermic reactions make interesting and exciting demonstrations of chemistry because the release of energy often includes sparks, flames, smoke or sound, in addition to heat. Reactions range from safe and gentle to dramatic and explosive.Exothermic reaction and some examples are explained here

Exothermic reaction of steel wool and vinegar

Steel rust is an example of an exothermic chemical reaction.
Steel rust is an example of an exothermic chemical reaction. 

Rust in iron or steel is an oxidation reaction – really a slower form of combustion . While waiting for rust to form would not be an attractive chemical demonstration, there are ways to speed up the process. For example. you can react the steel wool with the vinegar in a safe exothermic reaction which gives off heat.

See how to react steel wool and vinegar

Exothermic reaction of barking dog

This is called the barking dog because it is what the chemical reaction looks like.
This is called the barking dog because it is what the chemical reaction looks like. 

The “barking dog” reaction is a demonstration of preferred exothermic chemistry because it emits a sound “woof” or “bark”, similar to that of a dog. You will need a long tube of glass, nitrous oxide or nitric oxide and carbon disulfide for this reaction.

If you don’t have these chemicals, you can do another reaction using a bottle and rubbing alcohol. It’s not as loud or energetic, but it does produce a nice flame and an audible “woofing” sound.

  • How to do the Classic Dogking Barking reaction
  • Alternative barking dog reaction

Safe laundry detergent Exothermic reaction

Dissolving the laundry detergent in water is an exothermic reaction.
Dissolving the laundry detergent in water is an exothermic reaction. 

Probably the simplest and easiest exothermic reaction is the one you can try at home. Just dissolve the powdered laundry detergent in your hand with a small amount of water. Feel the heat?

Learn more about the exothermic laundry detergent reaction

Elephant toothpaste Exothermic reaction

Use a lower concentration of peroxide for the elephant toothpaste reaction if the children will be near the demonstration.
Use a lower concentration of peroxide for the elephant toothpaste reaction if the children will be near the demonstration. 

No list of exothermic reactions would be complete without the popular reaction of toothpaste to the elephant. The heat of this chemical reaction is accompanied by a foam fountain.

The classic form of the demonstration uses a solution of hydrogen peroxide, potassium iodide and a detergent. There is also a child-friendly version of the reaction that uses household yeast and peroxide and is safe enough for young hands to touch.

  • Try the elephant toothpaste reaction
  • Try the kid-friendly elephant toothpaste project

Exothermic reaction with sulfuric acid and sugar

Exothermic reaction with sulphuric acid .
The dehydrating sugar produces a memorable exothermic reaction. 

The reaction of sulfuric acid with ordinary table sugar (sucrose) results in an energetic exothermic reaction. Dehydrating the sugar pushes a steaming column of carbon black, the more it makes the whole room feel like burnt marshmallows.

Learn to make the reaction of sulfuric acid and sugar

Exothermic thermothermal reaction

Exothermic reaction example.
The thermite reaction produces a lot of light in addition to the heat. It is best to avoid looking directly at the flames. 

The thermite reaction is very similar to steel wool rusted with vinegar, except that the oxidation of the metal occurs much more vigorously. Try the thermite reaction, you want to burn metal and a lot of heat.

If you think “go big or go home”, then try the thermite reaction inside a block of dry ice. This amplifies the process and can even produce an explosion.

  • Steps to perform the thermite reaction (safely)
  • How to Make Etch a Thermite Crust

Sodium or other alkali metal in water

Like all alkali metals, potassium reacts vigorously in water during an exothermic reaction.
Like all alkali metals, potassium reacts vigorously in water during an exothermic reaction. 

If burning metals is your cup of tea, you can’t go wrong by dropping any alkali metal in the water (unless you add too much). Lithium, sodium, potassium, rubidium and cesium all react in water. When you lower the group into the periodic table, the energy of the reaction increases.

Lithium and sodium are relatively safe. Be careful if you try the project with potassium. It’s probably best to leave the exothermic reaction of rubidium or cesium in the water to people who want to become famous on YouTube. If it is you, send me a link and I will show your risky behavior.

Try the sodium in the water reaction (Safely)

Starting lights without matches

Exothermic reactions often burst into flames without the need for a match or other source of ignition.
Exothermic reactions often burst into flames without the need for a match or other source of ignition.

Some exothermic chemical reactions erupt spontaneously without the need for the aid of a lit match. There are many ways to make a chemical fire – all of them fantastic demonstrations of exothermic processes.

Learn how to make chemical fire without matches

Making hot ice is an exothermic reaction

Sodium acetate is also known as hot ice.An example of exothermic reaction
Sodium acetate looks like water ice, but crystallization from a supercooled solution makes these crystals hot rather than cold. 

Hot ice is what you get when you solidify sodium acetate from a supercooled solution. The resulting crystals resemble water ice, except that they are hot instead of cold. It’s a fun example of an exothermic reaction. It is also one of the common reactions used to make chemical hand warmers .

While you can buy sodium acetate, it is also very easy to make this chemical by mixing baking soda and vinegar and boiling the excess liquid.

Make hot ice

No more exothermic reactions to try

If you think about it, most chemical reactions absorb heat (endothermic) or release it (exothermic), so there are thousands of exothermic reactions you can try.
If you think about it, most chemical reactions absorb heat (endothermic) or release it (exothermic), so there are thousands of exothermic reactions you can try. 

Many chemical reactions release heat, so these popular exothermic reactions are not your only options. Here are some other interesting demonstrations to try:

  • Make Vesuvius Fire
  • Make a baking soda and vinegar (yes, it’s exothermic)
  • Magic Genie in a demonstration of bottled chemistry
  • Instant fire demonstration
  • Dance Rubber Bears
  • Dance charcoal
  • Thunderstorm test tube
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  • What is an endothermic reaction

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