Final answer:
To move a solid compound to the bottom of a melting point capillary tube, one should tap the open end on a hard surface. A needle can be used to adjust the position of the compound if necessary, without compacting it too much.
Step-by-step explanation:
To force a solid compound to the bottom of a melting point capillary tube, you should tap the open end of the capillary tube on a hard surface, such as a bench top. This action utilizes gravity to help settle the compound into the closed end of the tube. If the compound does not move down to the bottom, you can use a long, thin object like a needle to carefully push the compound down without compacting it too tightly, which could affect its melting behavior. Alternatively, tapping the closed end might cause some compacting and is not usually recommended for settling the compound.
While using the capillary tube, it's important to understand capillary action and the characteristics of liquid-glass interactions. For example, if a capillary tube is placed into a beaker of ethylene glycol, the ethylene glycol will rise into the tube by capillary action due to the strong adhesive forces between the polar Si-OH groups on the surface of glass and the molecules of the ethylene glycol, creating a concave meniscus. This is opposite to what happens with a nonpolar liquid like SAE 20 motor oil, which cannot form strong interactions with the polar Si-OH groups, resulting in the oil having a convex meniscus and a reduction in the capillary action.