What is a common tool for making powders in a laboratory setting?

In a laboratory setting, a mortar and pestle are commonly used for making powders due to their effectiveness in grinding and mixing solid substances. The mortar provides a stable base, while the pestle allows for controlled grinding action. This method is particularly useful for breaking down compounds into finer particles, which is essential for various applications such as preparing samples for analysis, creating homogeneous mixtures, or extracting active ingredients from plant materials.

While a blender can also create powders, it is generally more suited for liquids and might not achieve the same level of fine grinding as a mortar and pestle, especially for harder materials. A knife is not designed for powdering substances, and while a microwave can heat substances, it does not serve the purpose of reducing materials to a powdered form. Thus, the mortar and pestle are the most appropriate and traditional tools for this task in a laboratory context.