Crucible vs. Evaporating Dish — What's the Difference?

Crucibles are made from materials that can withstand extremely high temperatures, such as porcelain, quartz, or platinum, making them ideal for melting or ashing substances. They are typically used in applications where high heat resistance is crucial, such as in metal casting and chemical analysis. In contrast, evaporating dishes are usually made of porcelain or borosilicate glass and are used for evaporating solvents, usually at lower temperatures. They facilitate the slow evaporation process, which is essential in preparing concentrated solutions or in the drying of precipitates.

Evaporating dishes have a wide, shallow form to increase the surface area for evaporation, enhancing the evaporation rate. This design is particularly useful for concentrating solutions without the need for high temperatures. Crucibles, on the other hand, often have a higher form with a lid to contain substances at high temperatures and prevent contamination from the environment, which is not a design feature prioritized in evaporating dishes.

In terms of application, crucibles are essential in laboratories for tasks requiring high-temperature resistance, such as determining the melting points of metals or conducting gravimetric analysis. Evaporating dishes, however, are more commonly used in processes like crystallization, where a solvent is evaporated to leave behind a solid residue.

The choice between a crucible and an evaporating dish depends on the specific laboratory needs: high temperature and contamination prevention for the former, and effective solvent evaporation for the latter. This decision impacts the experiment's efficiency, safety, and outcome.

Both are crucial laboratory apparatuses, their care and handling differ due to their distinct functions and material compositions. Whereas Crucibles require conditioning before first use, especially when used at very high temperatures, to prevent cracking. Evaporating dishes, while also needing careful handling, primarily require gradual heating to avoid thermal shock and ensure a long service life.