To make a crucible oneself, one can start by obtaining a heat-resistant material such as clay, graphite, or silicon carbide. Then, the material can be shaped into a small, cylindrical container with a flat bottom and tall sides. The container can be fired in a kiln or furnace to harden the material and make it heat-resistant. Finally, the crucible can be cooled and then used for melting and casting metals or other high-temperature applications. **

Graphite for a crucible can be produced through a process called graphitization. This involves heating carbon materials, such as petroleum coke or coal tar pitch, to high temperatures in a controlled environment. The carbon material is first heated to around 3000 degrees Celsius to create a carbonized product, and then further heated to around 2500 degrees Celsius to convert it into graphite. This process allows for the carbon atoms to rearrange into the crystalline structure of graphite, resulting in a material with high thermal stability and resistance to chemical corrosion, making it suitable for use in crucibles. **

A graphite crucible will start to glow red at temperatures above 700 degrees Celsius. As the temperature increases, the intensity of the glow will also increase. At temperatures around 1000 degrees Celsius, the graphite crucible will emit a bright orange glow. **

You cannot melt iron in a copper crucible because iron has a much higher melting point than copper. Iron melts at around 1538°C, while copper melts at around 1085°C. This means that the copper crucible would melt before the iron reaches its melting point, making it impossible to contain the molten iron. Additionally, the two metals can form an alloy at high temperatures, which could contaminate the iron and affect its properties. **

A flower pot is not typically designed to withstand the high temperatures required for melting metals or other materials, which is a key function of a crucible. Crucibles are usually made of materials such as ceramic, graphite, or metal that can withstand extreme heat. Using a flower pot as a crucible could result in the pot breaking or shattering due to the high temperatures, making it unsuitable for this purpose. It is recommended to use a proper crucible made of heat-resistant materials for any melting or high-temperature applications. **

No, a portion of magnesium shavings does not become heavier if you burn them in a crucible and only occasionally ventilate the crucible lid. When magnesium burns, it combines with oxygen from the air to form magnesium oxide, which is a heavier compound than the original magnesium shavings. Therefore, the overall weight of the magnesium shavings will decrease as they burn and form magnesium oxide, rather than increase. Additionally, by occasionally ventilating the crucible lid, some of the magnesium oxide may escape as it is being formed, further reducing the overall weight of the shavings. **

To clean a crucible from sealing wax residue, you can start by gently scraping off as much of the residue as possible using a non-abrasive tool, such as a wooden or plastic scraper. Then, you can heat the crucible to a temperature just above the melting point of the sealing wax, allowing the remaining residue to melt and be wiped away with a clean cloth or paper towel. Finally, you can wash the crucible with warm soapy water to remove any remaining wax residue. It's important to avoid using abrasive materials or harsh chemicals that could damage the crucible. **

When magnesium shavings are burned in a crucible, they react with oxygen in the air to form magnesium oxide. This chemical reaction results in the magnesium combining with oxygen atoms from the air, increasing the overall mass of the substance. Therefore, the magnesium shavings become heavier when burned in a crucible due to the addition of oxygen atoms from the air during the combustion process. **