intermolecular forces
Rank the following substance from highest melting point to lowest melting point. My teacher gave a list of compounds: H2O, NO2,F2,CI2 and to have a high melting point means that you need a stronger IMF.
Rank the following substances from highest freezing point to lowest. Same compounds from above. What would I do in this instance?
Would I list this from lowest IMF to high IMF.
This must be a trick question. The melting point and the freezing point ARE THE SAME. By definition, the melting point is the temperature at which solid and liquid are in equilibrium. So whether the compound freezes or melts at that exact temperature depends only upon which way heat is flowing; i.e., in or out of the material. If it is flowing out, then the remainder of the material solidifies (freezes) and if heat is going in, the remainder of the material melts (becomes liquid). By the way, there is an error in the melting point order in your list. I don't know if the list you have is your ranking or if you are to rank them. Anyway, the highest to lowest is H2O, NO2, Cl2, F2. And you are right that the IMF determines the ranking. I looked up the melting points and they are as follows:
H2O, molar mass of 18, mp=0 degrees C.
NO2, molar mass of 46, mp=-11 degrees C.
Cl2, molar mass ~71, mp=-101
F2, molar mass 38, mp=-219
To rank the substances from highest melting point to lowest melting point, you need to consider the strength of intermolecular forces (IMFs) present in each compound. Generally, stronger IMFs lead to higher melting points. Here is the ranking from highest to lowest melting point:
1. H2O (water): Water has hydrogen bonding, which is the strongest type of IMF among the compounds listed. Therefore, it has the highest melting point among the given compounds.
2. NO2 (nitrogen dioxide): NO2 experiences dipole-dipole interactions, which are weaker than hydrogen bonding. Thus, it has a lower melting point compared to water.
3. F2 (fluorine gas): Unlike water and NO2, F2 does not have a permanent dipole moment. Instead, it exhibits London dispersion forces, which are weaker than dipole-dipole interactions. Therefore, F2 has a lower melting point than the previous compounds.
4. Cl2 (chlorine gas): Cl2 also experiences London dispersion forces. However, chlorine atoms are larger and have more electrons than fluorine atoms, which results in stronger London dispersion forces. Consequently, Cl2 has a higher melting point than F2, but still lower than water and NO2.
To rank the compounds from highest freezing point to lowest, you would follow the same logic as above since the melting and freezing points are essentially the same for a given compound. Therefore, the ranking from highest freezing point to lowest freezing point would be the same as the melting point ranking:
1. H2O
2. NO2
3. F2
4. Cl2
It is important to note that in both cases, the ranking is based on the strength of the IMF. So, the compounds with stronger IMFs will have higher melting (and freezing) points, while the compounds with weaker IMFs will have lower melting (and freezing) points.
To rank the substances from highest melting point to lowest melting point, you need to consider the strength of their intermolecular forces (IMFs). Generally, substances with stronger IMFs have higher melting points.
Here's how you can determine the rankings:
1. H2O (Water): Water molecules can form hydrogen bonds, which are the strongest type of IMF. Therefore, H2O has the highest melting point.
2. NO2 (Nitrogen dioxide): NO2 has a dipole-dipole interaction, which is weaker than a hydrogen bond but stronger than London dispersion forces. Therefore, it has a higher melting point compared to the remaining substances.
3. CI2 (Chlorine): Chlorine (CI2) only has London dispersion forces, which are the weakest type of IMF. Hence, CI2 has a lower melting point than H2O and NO2.
4. F2 (Fluorine): Fluorine (F2) also has only London dispersion forces, just like CI2. However, fluorine atoms are smaller and more electronegative than chlorine atoms, making the London dispersion forces slightly stronger. Therefore, F2 has a slightly higher melting point than CI2 but still lower than H2O and NO2.
To rank the substances from highest freezing point to lowest freezing point, you would follow the same principles as above since melting point and freezing point are essentially the same phenomenon. High melting point corresponds to a high freezing point.
Therefore, the ranking of the substances from highest freezing point to lowest freezing point would be the same as the ranking from highest melting point to lowest melting point:
1. H2O
2. NO2
3. CI2
4. F2
In both cases, you are essentially comparing the strength of the intermolecular forces (IMFs) in the substances to determine their relative melting or freezing points.