- Examples of chemical reaction experiments
- Hot ice
- Invisible Ink
- Bath bombs
- Styrofoam dissolution
- Dissolving the eggshell
- References
There are multiple chemical reaction experiments, which can be very simple to expose to awaken the interest of students or children for the subject, and can be carried out with complete safety both in laboratories and in the comfort of our kitchens.
Each chemical reaction separately has its methodology and the provisions that must be taken for the safety of those who carry out the experiment. Also, some experiments are likely to require hard-to-find materials or implements reserved for testing by professional chemists.
The rust cleaning of pennies is a chemical experiment that can be done anywhere. Source: Pixnio.
The more elaborate the preparation, as well as the more reactive the substances involved, the more complicated and dangerous the experiments will be. This is even more true if flammable gases are released in the process. But if that gas is carbon dioxide, then the experiments can be carried out in any space under proper supervision.
Here are five simple experiments that can be carried out at home, without the need for excessive expense or physical risks. One of the most common is the removal of the oxide layers of metals (such as that of pennies) with vinegar, soft drinks or citric acid, leaving its surface shiny and clean.
Examples of chemical reaction experiments
Hot ice
For the preparation of hot ice it will only be necessary: 1) a bottle of vinegar, from which we will take the amount of volume we want, 2) and baking soda. Both compounds are mixed in a container that will subsequently be heated, where they will react to form sodium acetate:
CH 3 COOH + NaHCO 3 => CH 3 COONa + CO 2 + H 2 O
Note that carbon dioxide, CO 2, observed as effervescence, will be released after mixing the vinegar (5% acetic acid) with the bicarbonate. In principle, it is advisable to add an excess of bicarbonate to ensure that all the acetic acid in our vinegar is neutralized.
We heat the mixture until a white salt begins to appear around the edges of the container: sodium acetate. We decant the liquid in another container, and once warm we cool it in the fridge.
This aqueous solution of CH 3 COONa is supercooled: it is unstable, and will freeze immediately and exothermically if we add a white crystal of CH 3 COONa. As you do so, the dissolved salt will be incorporated into the crystal, which acts as a seed and nucleation site for larger acetate crystals to grow.
The process is so fast that crystalline formations will be seen covering the entire volume of the container and generating hot ice due to the release of heat. The following video demonstrates what is explained here:
Invisible Ink
The invisible ink experiment is one of the most common and there are several methods to do it. They consist of moistening a brush or swab with a transparent liquid, which adheres to the paper, and by the action of heat, ultraviolet light, or the addition of another substance, it changes color, revealing the hidden message.
The most commonly used liquid is usually lemon juice. Moistening a brush with lemon juice proceeds to write the message on the paper. Then, using the heat of a light bulb or placing the paper in the vicinity of a flame (with great caution), the traces of lemon juice turn brown or black.
This is because heat breaks down the organic compounds in lemon to produce charcoal, which darkens the paper.
If ultraviolet light is used on the other hand, the lemon juice will absorb it, so even if the paper shines, the message will be revealed in dark letters. The invisible message can also be revealed if a natural indicator is poured over it; like grape juice or, even better, purple cabbage.
The following video shows precisely three ways to write invisible messages:
Bath bombs
Throwing large bath bombs into considerable volumes of water results in a spectacle of foam and colors. On small scales, however, they are easy to make anywhere if you have the right ingredients, which vary depending on personal preferences.
In a bowl mix the solid ingredients: citric acid and baking soda. If you want to add more weight to the resulting dough or protect it from moisture, you can add cornstarch or Epsom salt (magnesium sulfate).
In another bowl, proceed to mix the liquid ingredients: vegetable oil, essences, and food coloring.
The liquid mixture is then slowly poured into the bowl with the solid mixture, kneading it until it develops color and shape. Once this is done, you can create balls with it, or use molds to give them specific shapes. And voila, we'll have the bath bombs.
The liquid ingredients are those that provide the color and fragrances that you want to obtain when you throw the pump into the tubs or toilets. Meanwhile, the solid ingredients are responsible for the chemical reaction that takes place: in water, citric acid neutralizes sodium bicarbonate, releasing carbon dioxide again.
The following video shows step by step how to make bath bombs:
Styrofoam dissolution
Although it is not properly a chemical reaction, the observed effects are surprising to curious eyes. For this experiment, we will need Styrofoam (called anime in some countries) and acetone, a solvent that we find in nail polish remover.
In the following video you can see what happens when we try to dissolve large pieces of Styrofoam in a small volume of nail polish remover:
This material is practically air trapped in a thin polystyrene shell. Its nature is essentially apolar, so acetone, a nonpolar solvent, shows a high affinity for it. 'Like dissolves like', and because of that we see how foam dissolves in nail polish remover with the same ease with which sugar dissolves in water.
Dissolving the eggshell
This time, although it is a solution again, it does involve a chemical neutralization reaction: the acetic acid in the vinegar neutralizes the calcium carbonate in the eggshell:
CaCO 3 + 2CH 3 COOH => Ca (CH 3 COO) 2 + CO 2 + H 2 O
The reaction takes place when we deposit an egg in a glass with vinegar. Immediately, we will begin to appreciate the appearance of a layer of bubbles surrounding the shell of the egg; Such bubbles are due to CO 2 released from acid-base neutralization.
In this video we can see this experiment:
As the eggshell dissolves, only the membranes protect its interior, translucent, and through them we can see the yolk against the light.
These membranes are very delicate and slippery, but they still give the egg enough softness to allow it to bounce over short distances. If it is thrown from a great height, it will end up splitting, as shown in the video.
References
- Whitten, Davis, Peck & Stanley. (2008). Chemistry (8th ed.). CENGAGE Learning.
- Helmenstine, Anne Marie, Ph.D. (October 21, 2019). Easy Chemistry Experiments to Do at Home. Recovered from: thoughtco.com
- Adrian Dinh. (December 1, 2014). 8 simple chemistry experiments that your kids can do at home. Recovered from: 3plearning.com
- Stepp, Sue. (January 08, 2020). Easy and Fun Chemical Reaction Experiments. sciencing.com. Recovered from: sciencing.com
- Bayer US. (December 29, 2017). Salt Crystals Experiment. Recovered from: thebeakerlife.com
- Lindsey E. Murphy & CrazyAuntLindsey.com. (November 3, 2011). Invisible Ink Reveals Cool Chemistry. Recovered from: scientificamerican.com