What Is the Purpose of Melting Points?

Observe Unkown Substances

• One key purpose of a melting point is to observe the characteristics of an unknown substance. This can help to give clues about the composition of the materials, or at minimum, provide an idea of what other properties it might have. Scientists should consider finding the freezing point of an unknown substance as well to provide greater insight into the composition of the material.

Identify a Solid

• Melting and freezing points can also be used to identify an unknown solid. Determining the melting point narrows the different possibilities of the type of composition. It can also alert a scientist to the fact that he has discovered a new compound. Another differentiation to help determine the material is the time that it takes for a material to begin melting until it is completely melted. This observation can also provide a clue to the nature of the element.

Level of Purity

• Another reason for determining a boiling point is to determine its level of purity. Samples often have mixtures of several different elements, especially if they are found in nature. For example, if you are provided with iron ore and believe that it has other elements in the sample, you can determine the melting point. If the experimentally derived melting point differs significantly from the expected melting point, then the sample is highly impure with other elements.

Calculation

• The melting point of a material can be calculated by a simple formula. It can be found by dividing the Boltzman constant by the thermal energy. The formula is:

  T = E/k

  This calculation was discovered by Fredrick Lindemann in 1910. The Boltzman constant is a static number, while thermal energy can be derived from another set of calculations if it is not available.