How does molar mass affect the boiling point of covalent substances?
The general rule is that heavier molecules boil at a higher temperature.
thanks
You're welcome! To understand how molar mass affects the boiling point of covalent substances, we need to consider the concept of intermolecular forces.
In covalent substances, intermolecular forces are the attractive forces between molecules. These forces generally include London dispersion forces, dipole-dipole interactions, and hydrogen bonding. The strength and type of intermolecular forces vary depending on the composition and structure of the substance.
Molar mass, or the mass of one mole of a substance, affects the boiling point because it influences the strength of the intermolecular forces.
Heavier molecules have more electrons and larger atomic or molecular structures, which result in stronger London dispersion forces. London dispersion forces are caused by temporary fluctuations in the electron distribution within a molecule. These forces become stronger as the molar mass increases, leading to stronger attractions between the molecules. Consequently, a substance with a higher molar mass will generally require more energy to overcome these stronger intermolecular forces and reach its boiling point.
However, it is important to note that molar mass is not the sole factor determining the boiling point. The molecular structure and the presence of other intermolecular forces, such as dipole-dipole interactions or hydrogen bonding, also play significant roles.
To summarize, in covalent substances, heavier molecules with higher molar masses tend to have higher boiling points due to the increased strength of the intermolecular forces, primarily the London dispersion forces.