(i) For each of the two processes, identify the type(s) of intermolecular or intramolecular attractive forces that must be overcome for the process to occur. In process 1, hydrogen bonds (or dipole-dipole interactions ) in liquid water are overcome to produce distinct water molecules in the vapor phase.
Strong intermolecular forces produce a lower rate of evaporation and a lower vapor pressure. Weak intermolecular forces produce a higher rate of evaporation and a higher vapor pressure. As the temperature increases, the vapor pressure increases.
In water a H2O molecules from four hydrogen bonds with neighboring water molecules, so melting ice involves the breaking of hydrogen bonds, in addition to dispersion interaction. Therefore the intramolecular forces that have to overcome during the melting ice are dispersion, dipole-dipole interaction and hydrogen bond.
A hydrogen bond is broken when water vaporizes. Hydrogen bonds are weak bonds between the two water molecules.
In liquid water, water molecules are continually forming and breaking hydrogen bonds. In water, a hydrogen bond has a bond energy of about 0.2 eV (binding energy of -0.2 eV).
In order from strongest to weakest, the intermolecular forces given in the answer choices are: ion- dipole, hydrogen bonding, dipole-dipole, and Van der Waals forces.
Dipole-dipole interactions are the strongest intermolecular force of attraction.
As alcohol evaporates at a much faster rate compared with water due to its lower boiling temperature (82 compared to 100 degrees C), it is able to carry away more heat from the skin. This means for a given amount of time much more alcohol evaporates than water.
For molecular substances that contain molecules of about the same size, substances with hydrogen bonds have stronger attractions between the particles than substances with either dipole – dipole attractions or London forces, and substances with dipole – dipole attractions have stronger attractions between the particles
The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.
The boiling points of NH3, H 2O, and HF are abnormally high compared with the rest of the hydrides in their respective periods.” is the strongest evidence for hydrogen bonding.
Hydrogen bonds are strong intermolecular forces created when a hydrogen atom bonded to an electronegative atom approaches a nearby electronegative atom. Greater electronegativity of the hydrogen bond acceptor will lead to an increase in hydrogen – bond strength.
Since boiling does not break the bonds in a water molecule, the bubbles are composed of water vapor. In contrast, within liquid water, there is a chemical reaction that is going on – the disassociation of water into –OH and H+, which we will discuss in more detail shortly.
To make water evaporate, energy has to be added. The water molecules in the water absorb that energy individually. Due to this absorption of energy the hydrogen bonds connecting water molecules to one another will break. The molecules are now in the gaseous state; this is called water vapour.
When a liquid boils, the intermolecular bonds are broken, and the molecules are dispersed in the gas phase. A stronger intermolecular bond requires more energy to break, and a higher temperature is required to provide this energy. Thus, molecules with stronger intermolecular bonds have higher boiling points.