Melting Points and Recrystallization

This set of flashcards covers key concepts related to melting points and recrystallization, including definitions, phenomena, and procedures.

What is the definition of melting point?

The melting point is the temperature range at which a solid and its liquid are in equilibrium at a total pressure of 1 atmosphere.

What happens when a solid melts into a liquid?

Intermolecular forces of attraction between molecules are broken due to supplied energy, allowing the molecules to have more degrees of freedom.

What are some examples of intermolecular forces?

Hydrogen bonds, dipole-dipole interactions, and induced dipole interactions (van Der Waals forces).

What is melting point depression?

A phenomenon where the melting point range of a mixture is lower and broader than that of either pure component.

What is a eutectic point?

The lowest melting point obtained from a binary mixture of two compounds, determined through experimentation.

How does impurity affect the melting point of a solid?

Impurities typically lower the melting point and broaden the melting range due to weaker interactions.

What is the purpose of grinding a solid sample into fine particles for melting point determination?

To ensure uniform melting; larger particles can give rise to an artificially large melting point range.

What apparatus is used for determining melting points?

A MelTemp apparatus is used, which consists of a capillary melting point tube, a heated metal plate, and a thermometer.

What should be avoided when heating a sample in the MelTemp apparatus?

Heating too quickly, as it may cause the sample to melt at a lower temperature and over a broader range.