Answer:
The greater the polarity(the difference in electronegativity of the atoms in the molecule) , the stronger the dipole-dipole attraction.
Dipole-dipole attractions are very weak and substances held together by these forces have low melting and boiling point temperatures. Generally, substances held together by dipole-dipole attractions are gases at room temperatures. Therefore, we can conclude that the intermolecular force between the oxygen and the nitrogen, which are both gases at room temperature , and have low boiling points, is a dipole-dipole attraction.
2. The hydrogen sulfide molecule (H2S) and the water molecule (H2O) are very similar. However, the boiling point of hydrogen sulfer is -60 degrees celsius whereas the boiling point of water is 100 degrees celcius. How can the intermolecular forces explain this difference?
In a water molecule there are two H atoms and one O atom. The O atom has two lone pairs thus each water molecule can form up to 4 hydrogen bonds with the surrounding water molecules. Hydrogen sulfide does not form any hydrogen bonds. Therefore it has a smaller boiling point then water.
3. Iodine solid sublimes to iodine gas. What happens in terms of intermolecular forces as this process occurs?
Sublimation is the apparent direct change from solid to gas phase. .
Consider the particles in a solid: They are fixed in position, they vibrate in place.
Consider the particles of a gas: they are free to move anywhere in the container, they are moving rapidly.
Take iodine as an example because it is so easy to see. The solid is a blue-black crystal. The gas is a purple vapor.
In sublimation, the particles go directly from the solid crystal to the gas without melting.
At room temperature iodine crystals I2 (s) sublime
Consider the particles in a solid: They are fixed in position, they vibrate in place.
Consider the particles of a gas: they are free to move anywhere in the container, they are moving rapidly.
Take iodine as an example because it is so easy to see. The solid is a blue-black crystal. The gas is a purple vapor.
In sublimation, the particles go directly from the solid crystal to the gas without melting.
At room temperature iodine crystals I2 (s) sublime
