Place the following compounds in order of increasing strength of intermolecular forces. co2 f2 nh2ch3 a) nh2ch3 < co2 < f2 b)

Place the following compounds in order of increasing strength of intermolecular forces. co2 f2 nh2ch3 a) nh2ch3


It should be D) since NH2CH3 has hydrogen atoms in the formula, it will tend to be polar-so dipole-dipole, dispersion forces are always there, and then hydrogen bonding is the strongest intermolecular force. There are no Ion-dipole attractions present in any of these compounds. F2 should have the weakest strength in Intermolecular forces, since it is not polar so only dispersion forces should be found present. Which leaves CO2 to be in the middle with Dipole-dipole attractions and dispersion forces.

CH3(CH2)8CH3 > CH3CH2CH2CH3 > CH3CH3 (Option f)


Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles.

CH3CH3 has a molar mass of 30.07 g/mol

CH3(CH2)8CH3 has a molar mass of 142.28 g/mol

CH3CH2CH2CH3 has a molar mass of 58.12 g/mol

CH3(CH2)8CH3 > CH3CH2CH2CH3 > CH3CH3 (Option f)

CH3Cl < CH3OH < NaCl


The intermolecular forces are the forces that join together the ions, metals, or molecules in a substance. At a metallic substance, the forces involved are the metallic forces. In the ionic compounds, the forces are the ion-ion forces, and at molecular compounds, there're three different types of forces.

The intermolecular forces of a molecule can be the London force, dipole-dipole force or hydrogen bond. The London force happens in nonpolar substances, the dipole-dipole forces at polar substances, and the hydrogen bond, at polar substances that have the hydrogen-bonded to a high electronegative element (N, O, or F).

The order of increasing strength is:

London force < dipole-dipole < hydrogen bond < metallic < ion-ion.

CH3Cl is a polar molecule because its dipole moment is different from 0 (the dipole of C-Cl is strong than the dipole of C-H so they don't cancel each other). Thus, it has dipole-dipole forces.

NaCl is an ionic compound formed by the ions Na+ and Cl-, so it has ion-ion forces. Ah CH3OH is a polar molecule, in which the hydrogen is bonded to oxygen, so it has hydrogen bonds. The increasing strength of intermolecular forces is:

CH3Cl < CH3OH < NaCl

CH4 < CH3CH3 < CH3CH2CH3


Alkanes are saturated aliphatic hydrocarbons that undergoes intermolecular Van der waals forces. Van der waals forces are the attractive forces which make it possible for non-polar molecules to form liquids and solids.

Van der waals force are described as intermolecular forces arising from induced fluctuating dipoles in atoms and molecules brought about by movement of electrons around the atomic nucleus.

An example of the Van der waals force is the  london dispersion force that occurs in the alkane family. It is the weakest of all electrical forces that act between atoms and molecules, These forces are responsible for liquefaction or solidification of non-polar substances at low temperature.

The strength of the intermolecular forces is based on the number of electrons surrounding the molecule and the surface area of the molecule. SO, in alkanes, the longer the carbon chain, the more stronger the intermolecular forces.

CH4 < CH3CH3 < CH3CH2CH3


Alkanes are the simplest hydrocarbons (compounds of C and H), they have no functional group and the bonds between carbon atoms (with sp3 hybridization) are simple bonds, each orbital is directed to the vertices of a tetrahedron. Each orbital forms a σ bond with each H.

Alkanes may have a straight or branched chain. When the compounds have the same molecular form and only differ in the order in which the atoms in the molecule are linked, they are called constitutional or structural isomers.

The interaction between molecules (intermolecular forces) is a balance between the repulsion of the external electrons and the attraction of the nuclei of a molecule on the electrons of which they are close.

Alkanes without electronegative atoms have a relatively dense and continuous "shell" of electrons. The repulsion of electronic clouds is important and therefore the attraction between alkane molecules is very weak.

The "shape" of the molecules affects the contact surface. What do these experimental data suggest? Unbranched molecules, with linear zigzag structure, attract more effectively.

In other words, the longer the C chain in alkanes increases the intermolecular forces.


More is the mass of an alkane molecule more will be its boiling point. This means that forces of attraction will be more when mass is more as more heat is required to break the bonds within atoms. Hence, boiling point is more.

Therefore, in the given molecules mass of CH_{4} is 16.04 g/mol, mass of CH_{3}CH_{2}CH_{3} is 44 g/mol, and mass of CH_{3}CH_{3} is 30 g/mol.

Thus, we can see that CH_{3}CH_{2}CH_{3} has the highest mass and CH_{4} has least mass.

Hence, increasing strength of intermolecular forces of given compounds is as follows.

             CH_{4} < CH_{3}CH_{3} < CH_{3}CH_{2}CH_{3}          

pentane < butanal < 1-butanol


The intermolecular forces are the forces that bind together the molecules in a substance, and its strength depends on the polarity of the molecule. The polarity is given by the dipole moment, which is the vector sum of the dipoles of the bonds. The dipole is the difference of electronegativity between the elements of the bond. So, if the dipole moment is 0, the molecule is nonpolar, and if it's different from 0 the molecule is polar and has partial charges.

The nonpolar molecules have the weakest force, which is called London forces, or dipole induced-dipole induced forces. The polar molecules have dipole-dipole forces, which is stronger than the London forces. If the polar molecules have the hydrogen-bonded to a high electronegative element, thus, this dipole-dipole bond is extremely strong, and it's called a hydrogen bond.

Butanal has the oxygen bonded to carbon, and the hydrogen-bonded to carbon too. The dipole at carbon-carbon is 0, and the dipole of H-C is canceled, but the dipole of C=O is different from 0, so, the molecule is polar, and has dipole-dipole force.

1-butanol has a bond O-H, so it has a hydrogen bond, and pentane only has bonds between C-C, which are nonpolar, and the bonds C-H have its dipole canceled, thus the molecule is nonpolar, and has London force. So, the order of increasing strength is:

pentane < butanal < 1-butanol

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