Hello, I need help solving this problem on intermolecular dispersion forces. Can you explain how I go about finding the answer?

Which member of the following has the stronger intermolecular dispersion forces?
a. CO
neither of these

neither of these

c. CH3Br
neither of these

For CO2 vs CO, look at the structure. CO is a linear molecule (it must be because that is the only way to put two atoms together). Since the electronegativity of C is about 2.4 and that of O is about 3.5, the CO molecule is a dipole (it is a polar bond) because of the separation of charge. For the CO2 molecule; however, it is O=C=O and any dipole between the O=C on the left is canceled by the dipole between the C=O on the right; therefore, CO2 is not a polar molecule. It has a zero dipole moment. That is, CO molecules are polar and there is an attraction between polar molecules. CO2 is not polar and there is little attraction between molecules. Therefore, CO has the larger intermolecular force. For b, the same kind of reasoning except in this case one chain is longer than the other. So which molecule is the more polar? That will be the one with the larger intermolecular force. c is the same kind of thing but in this case compare the electronegativity of Br with that of Cl to get the more polar molecule. I hope this helps.

yea i got it


Certainly! When comparing the strength of intermolecular dispersion forces between different molecules, we need to consider the factors that affect the strength of these forces.

Intermolecular dispersion forces, also known as London forces or Van der Waals forces, are temporary attractions between molecules that arise from the fluctuations in electron distribution. These forces occur in all molecules, regardless of their polarity.

The strength of intermolecular dispersion forces generally increases with the size of the molecules involved. Larger molecules have more electrons, leading to increased electron density, and therefore stronger dispersion forces.

To determine which molecule has stronger intermolecular dispersion forces in each case, we can compare their molecular sizes.

a. CO vs. CO2:
CO and CO2 have comparable molecular sizes since both molecules consist of three atoms. Therefore, they will have similar strengths of intermolecular dispersion forces. So, the answer is neither of these.

b. CH3CH2CH2CH2Br vs. CH3CH2CH2Br:
In this case, CH3CH2CH2CH2Br is larger than CH3CH2CH2Br since it has an extra carbon atom. Therefore, CH3CH2CH2CH2Br will have stronger intermolecular dispersion forces. So, the answer is CH3CH2CH2CH2Br.

c. CH3Br vs. CH3Cl:
CH3Br and CH3Cl have the same number of carbon atoms but differ in the halogen atom being bromine (Br) and chlorine (Cl), respectively. Bromine is larger and has more electrons than chlorine, resulting in CH3Br having stronger intermolecular dispersion forces. So, the answer is CH3Br.

In summary, the molecule with the stronger intermolecular dispersion forces is:
a. Neither of these (CO and CO2)
b. CH3CH2CH2CH2Br (between CH3CH2CH2CH2Br and CH3CH2CH2Br)
c. CH3Br (between CH3Br and CH3Cl)