Rank the following molecules in order of increasing boiling point.
NH3, CaCl2, Ar, CO, HF
This is what I have, am I correct or on the right track?
CaCl2, HF, NH3, CO, Ar
I think Ar is higher than CO.
ca,na,zn,cu,Ag,pd
at the right back
You are on the right track, but there are a couple of adjustments needed. To determine the order of increasing boiling points, we need to consider the intermolecular forces present in each molecule.
Intermolecular forces play a significant role in determining the boiling point of a substance. The stronger the intermolecular forces, the higher the boiling point.
Let's analyze the given molecules one by one:
1. NH3 (Ammonia) - Ammonia is a polar molecule with a lone pair of electrons on the nitrogen atom. It can form hydrogen bonds between the hydrogen atom and the lone pair of another ammonia molecule. Hydrogen bonding is a strong type of intermolecular force. Therefore, NH3 has relatively high boiling point compared to other molecules on the list.
2. CaCl2 (Calcium Chloride) - Calcium chloride is an ionic compound that forms a crystal lattice structure. The attractive forces within the crystal lattice are ionic bonds, which are very strong. However, since we are comparing boiling points, we need to consider the forces between individual molecules. The ionic bonds holding the solid lattice together need to be broken in order to convert the solid into a liquid. This means that the boiling point of CaCl2 is relatively high.
3. Ar (Argon) - Argon is a noble gas and exists as individual atoms rather than molecules. It is nonpolar, and the only intermolecular force acting between argon atoms is weak van der Waals forces (London dispersion forces). These forces are relatively weak, resulting in a lower boiling point compared to the previous two molecules.
4. CO (Carbon Monoxide) - Carbon monoxide is a linear molecule with a polar bond between carbon and oxygen. It can experience dipole-dipole interactions, but not as strong as hydrogen bonding in NH3. The boiling point of CO is higher than Ar but lower than NH3 and CaCl2.
5. HF (Hydrogen Fluoride) - Hydrogen fluoride is a polar molecule with a strong dipole moment. It can form hydrogen bonds due to the presence of fluorine's lone pair of electrons. HF has the highest boiling point among the given molecules.
Considering the above analysis, the correct order of increasing boiling points for the given molecules is:
Ar < CO < CaCl2 < NH3 < HF