Question

1. refer to figure 1. what causes a difference in boiling point between methanol, ethanol, and propanol? the strength of the attractive forces between the molecules the type of intermolecular forces present the repulsion between protons and the electrons within each atom the atomic number of each of the elements

Explanation:

Methanol (\(CH_3OH\)), ethanol (\(C_2H_5OH\)), and propanol (\(C_3H_7OH\)) all have hydrogen - bonding (a type of intermolecular force) due to the \(-OH\) group. But as the carbon - chain length (molecular size) increases from methanol to ethanol to propanol, the London dispersion forces (another type of intermolecular force, which depend on molecular size and surface area) increase. The overall intermolecular attractive forces (a combination of hydrogen - bonding and London dispersion forces) become stronger with increasing carbon - chain length. Boiling point is related to the strength of the attractive forces between molecules. Stronger intermolecular attractive forces require more energy (higher temperature) to separate the molecules and convert the liquid to a gas.
The type of intermolecular forces (all have hydrogen - bonding) is not the differentiating factor here. The repulsion between protons and electrons within each atom is not relevant to the boiling - point difference among these molecules. The atomic number of elements in the molecules is not the direct cause of the boiling - point difference.

Answer:

The strength of the attractive forces between the molecules.