How to predict which substance in each of the following pairs would have the greater intermolecular forces ? a) #CO_2# or #OCS#; b) #SeO_2# or #SO_2#; c) #CH_3CH_2CH_2NH_2# or #H_2NCH_2CH_2NH_2#; d) #CH_3CH_3# or #H_2CO#; e) #CH_3OH# or #H2CO#.

Answer 1

VERY LONG REPLY

A molecule's polarity and capacity to form hydrogen bonds are directly correlated with the strength of the intermolecular forces it exhibits.

When compared to polar molecules of similar size, nonpolar molecules will initially have weaker intermolecular forces.

This is a quick analysis of each pair, with the molecule with the higher IMFs indicated in green.

You're dealing with two linear molecules, the only difference between the two being that #CO_2# is nonpolar, while #OCS# is polar.
In #CO_2#'s case, the bond dipole moments are equal in magnitude and point in opposite directions, so the net dipole moment will be zero. In #OCS#'s case, the bond dipoles are not equal in magnitude because sulfur and oxygen has different electronegativity values.

This one is a little more nuanced; selenium and sulfur are very similar from an electronegativity stanpoint, and both molecules have a bent molecular geometry, indicating that they are polar.

But selenium is more polarizable than sulfur because it has a larger radius, which suggests that it also has a larger electron cloud.

Due to the selenium atom's slightly larger positive charge than the sulfur atom's, there will be a marginally larger net dipole moment.

This is where the ability to form hydrogen bonds comes into play. The difference between these two amines will be made by the additional #"-NH"_2# functional group present on ethylenediamine.
This second #"-NH"_2# group will provide ethylenediamine with the capability to form more hydrogen bonds with neighbouring molecules when compared with propylamine, the compound that only has one #"-NH"_2# group attached.
Methane, or #CH_3CH_3#, is a nonpolar molecule because the #"C-H"# bonds are considered to be nonpolar. As a result, methane will only exhibit weak London dispersion forces.

On the formaldehyde molecule, on the other hand, the electronegative oxygen will produce a permanent dipole moment, enabling the molecule to display dipole-dipole interactions in addition to the London dispersion forces that all molecules display.

Once again, this comes down to the ability to form hydrogen bonds. Both molecules exhibit London dispersion forces and dipole-dipole interactions, but the fact that ethanol, #CH_3OH#, has a hydrogen atom directly attached to an oxygen atom will allow it to engage in hydrogen bonding.
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Answer 2

a) OCS would have greater intermolecular forces than CO2 due to the presence of polar bonds and a permanent dipole moment. b) SO2 would have greater intermolecular forces than SeO2 due to stronger dipole-dipole interactions resulting from its bent molecular geometry. c) H2NCH2CH2NH2 would have greater intermolecular forces than CH3CH2CH2NH2 due to hydrogen bonding between the nitrogen and hydrogen atoms. d) H2CO would have greater intermolecular forces than CH3CH3 due to the presence of polar bonds and a permanent dipole moment. e) CH3OH would have greater intermolecular forces than H2CO due to hydrogen bonding between the oxygen and hydrogen atoms.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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