What do marble, chalk, and eggs have in common?

Описание: Reagents and equipment:
*Synthesizing calcium carbonate:
0.17% calcium hydroxide solution, carbon dioxide, and a test tube
*Dissolving calcium carbonate (marble):
Calcium carbonate (marble), 10% hydrochloric acid solution, and a beaker
*Rubber egg experiment:
chicken or quail eggs, 9% acetic acid solution (vinegar), a glass
*Flammable gel experiment:
50 g crushed eggshell, 50 mL 70% acetic acid solution, 60 mL water, 150 mL 96% ethyl alcohol, a glass, a wooden stick, a lid that fits the glass, and a glass container.
*Glowing marble:
Marble, a blowtorch, a heat-resistant work surface, and metallic tweezers
*Synthesizing calcium carbonate:
Bubble carbon dioxide through a 0.17% calcium hydroxide solution. Watch as the solution becomes cloudy.
*Dissolving calcium carbonate (marble):
Place a piece of calcium carbonate (marble) in a beaker and add a 10% hydrochloric acid solution. Watch the resulting vigorous release of gas.
*Rubber egg experiment:
Place an egg in a glass and add a 9% acetic acid solution (vinegar). Leave it there until the eggshell dissolves completely, at least six hours. The duration of this experiment will depend heavily on the thickness of the shell. Take the egg out of the glass and rinse it thoroughly with water. Note that the shell has dissolved, and the egg has become rubbery.
*Flammable gel experiment:
Pour 50 g of crushed eggshell into a glass and add 50 mL of 70% acetic acid solution. Now add 30 mL of water. Close with a lid and leave for a week — be sure to keep away from children and animals. A week later, add 30 mL of water and mix thoroughly. Filter the resulting solution through a funnel with cotton wool. Pour the solution into a bowl and add 100 mL of ethyl alcohol. In several seconds, the solution will turn into gel.
*Glowing marble:
Heat a piece of marble with a blowtorch. When you stop heating the stone, you should see it glowing. Conduct this experiment in a darkened room.
*Synthesizing calcium carbonate:
When carbon dioxide is bubbled through a calcium hydroxide solution, it produces calcium carbonate, which dissolves poorly in water and therefore precipitates out.
Ca(OH)2 + CO2 = CaCO3 + H2O
*Dissolving calcium carbonate (marble):
Calcium carbonate reacts with hydrochloric acid, forming unstable carbonic acid, which dissociates into carbon dioxide gas and water:
CaCO3 + 2HCl = CaCl2 + CO2 + H2O
*Rubber egg experiment:
An eggshell contains calcium carbonate, which dissolves readily in vinegar with a release of carbon dioxide:
СаСО3 + 2СН3СООН = Са(СН3СОО)2 + СО2 + Н2О
Only a thin film is left at the end. This film keeps the egg from leaking out and turns it into something resembling a ball!
*Flammable gel experiment:
If you add ethyl alcohol to the calcium acetate solution produced by dissolving an eggshell in acetic acid, it will form a flammable gel that can be used as a solid fuel.
The gel forms via the solvation of calcium ions by ethyl alcohol molecules, a process in which the molecules of ethyl alcohol surround the calcium ions from all sides.
Such a gel should be stored in an airtight container to prevent the alcohol from evaporating.
*Glowing marble:
Marble in the Earth’s crust receives small doses of energy, such as small amounts of radiation. Though this radiation doesn’t make the marble radioactive, it provides additional energy to atoms in the marble’s structure, and some electrons in these atoms remain in an excited (unstable) state. When heated, marble releases this energy with a visible glow.
Applications:
*Calcium carbonate is also used to refine sugar. In a prepared sugar syrup, calcium carbonate particles adhere to impurities and precipitate down to the bottom.
*In the medical industry, calcium carbonate is used to treat the excessive acidity of gastric juices. It neutralizes the hydrochloric acid found in the stomach
*Mixed with water, calcium carbonate is used as a paint, sometimes known as "whiting."
*It is included as an abrasive component in numerous household cleaning powders.
*Calcium carbonate can be harmful as well – it is found in the scale that forms in water heaters because of hard water.
*Due to its softness, calcium carbonate in the form of chalk is often used for writing and drawing.
*The hardness of marble, which is also calcium carbonate, found use in sculpture. For instance, the Lincoln Memorial in Washington, D.C. is made of marble.
*The skeletons of stony corals consist almost entirely of calcium carbonate.


Safety precautions: Wear protective gloves, a mask, and safety glasses. Work in a well-ventilated area. Observe safety measures when working with fire and hot objects.