In itself, the expression "hot ice" hardly fits in our heads. After all, we are used to the fact that ice, no matter if it is a small cube in a glass or a huge iceberg in the ocean, is icy. And for some reason it's hot. Let's figure out what kind of substance it is, how it turns out and conduct an experiment at home. So - hot ice.
A substance with that name
Everyone knows perfectly well that ice is water in a solid state of aggregation, into which it passes already at 0 °C. But, while conducting experiments on water, the English physicist Bridgman discovered that under high pressure, the crystal lattice is rearranged, it becomes denser.
Under a pressure of slightly less than 21,000 atmospheres, water becomes ice already at a temperature of +76 °C. And at 30 thousand atmospheres - at 180 ° C! This is really hot ice. You can get burned a lot. But it is impossible to touch him, because it is unrealistic for a person to withstand such pressure. Physicists are studying the properties of such iceonly indirectly.
Thanks to experiments, the Englishman determined that there are several types of ice, where under grade I is the familiar ice formed at zero, and then, with increasing pressure, it passes from one grade to another. At 30 thousand atmospheres, it becomes grade VII. Since the crystal lattice changes, the properties of hot ice are different. It is heavier than water and has a density of 1.05 g/cm3.
Another substance with the same name
To conduct the "Hot Ice" experiment at home to test Bridgman's theory, of course, will not work. But chemistry as a science offers you a different experience, no less spectacular.
It's called "Hot Ice". Sodium acetate is the substance you will need to carry it out. Did not hear? And in the kitchen, we often get it when preparing various pastries, mixing soda and vinegar. It remains only to figure out how to make hot ice from this foam. Let's figure it out.
Formula and reaction equation
Sodium acetate (also called the sodium s alt of acetic acid) is white crystals with a slightly s alty taste and an odor that resembles vinegar. Its formula is CH3COONa. In the laboratory, s alt is made from acetic acid and carbonates, sodium hydroxide, or sodium bicarbonate.
For those who are interested, the reaction equation is as follows:
CH3COOH + NaHCO3 → CH3-COON a + H 2O + CO2
Mistresses know that the percentageacetic acid may be different. But there is no difference what you find in the cabinet in the kitchen, you just need a different amount of soda. The proportions are as follows:
- 750 g of vinegar 8% and 84 grams of soda;
- 86 g of essence 70% and 84 grams of soda;
- 200 g vinegar 30% and 87.4 g soda.
As a result of the reaction we get a solution, but by evaporating the water we get 82 g of sodium acetate in the form of crystals.
Chemistry is a science that does not tolerate the "pour on the eye" option. If you want the chemical experiment "Hot Ice" to be a success, make up a proportion of the substances using weights. More accurate are electronic.
Experience at home
Since acid is used during the experiment, and the "Hot Ice" experiment also requires heating to high temperatures, the presence of adults is mandatory. So, let's get down to witchcraft.
Cooking "Hot Ice" at home.
- In a small enamel saucepan, combine vinegar and soda in the proportions indicated above, depending on the percentage of vinegar found in the kitchen. Put it on the stove, on a small fire and heat the resulting magical brew a little. Get ready, there will be a lot of foam, but as soon as the reaction passes and there is water and sodium acetate in the pan, the solution will become completely transparent.
- Be sure to check if your solution is ready by dropping a drop of vinegar. Got foam? So, the wrong weight of soda was initially taken, we continue a little bitadd vinegar until the foam stops appearing. Well, if the smell of vinegar hits the nose very strongly, it means that a lot of acetic acid was taken initially. Add a little soda to the solution until the foam stops forming in the saucepan, otherwise the smell of vinegar from the apartment will take a long time to erode.
- Only when the foam has stopped rising, the saucepan with the brew can be put on fire to remove excess water from it. Don't forget to follow what's going on. As soon as a crust similar to ice begins to form on the surface, immediately remove the container from the fire and leave it alone for 5 minutes.
- While the magical drink is cooling down, put water in the teapot to boil. Then slowly, literally drop by drop, we begin to pour boiling water into the already cooled mixture, alternating addition with stirring. We do the procedure until the crust and all visible pieces are completely dissolved. The solution should be completely clear, but slightly viscous.
- We take an absolutely clean container and pour a small amount of the substance from the saucepan into it. If the jar or mug turns out to be dirty, the solution will not crystallize when you want, but for now it will be cooled. Put in the refrigerator and cool to room temperature. We need to understand that we have a supersaturated solution, so now the temperature of the crystallization process is lower than usual.
- Chilled out? Here it is, the moment of truth. It's time to begin the mystery of the formation of hot ice!
Touch the chilled brew with a toothpickpoint in table s alt. If everything is done correctly, the solution will begin to harden, forming a pattern of ice-like crystals, each time new and unique. This releases a large amount of energy that you will feel as a wave of heat.
After the formation of hot ice, it can be used to repeat the experiment. Just put the container in a water bath and start stirring with a spoon. Did you see that a crust of crystals formed? Repeat steps 4-6 and enjoy the result again and again.
Why did the experiment fail? Troubleshooting
There are not so many options why the experience did not turn out, but we will consider them all:
- When soda reacted with vinegar, some reagent turned out to be in excess and affected the further preparation of a supersaturated solution. Next time, keep a close eye on the amount of substances in the preparation, or just buy the sodium s alt of acetic acid in ready-made form.
- The container in which the prepared solution was cooled turned out to be contaminated.
- The saucepan was removed from the heat too late, or the resulting crust was not completely dissolved.
Where is this reaction used?
The "Hot Ice" experience itself also has practical applications, it is a supersaturated solution that is used in chemical heating pads and heaters, which, as you yourself saw, does not go into a solid phase.
Only in heating pads you act on the solution not with a toothpick, but with a specialdisk (most often metal). During the transition of a supersaturated solution to the solid phase, from 264 to 289 kJ/kg is released. So you formed "hot" ice, and the heating pad acts on the body with the generated heat, while the burn is excluded, since the generated temperature is not enough.
By the way, as a source of heat, a supersaturated solution of sodium acetate is also used in some models of spacesuits. "Hot ice" rules.
