imagine replacing one H atom of a methane molecule, ch4, with another atom or group of atoms. Account for the order in the normal boiling points of the resulting compounds:CH4(-161 celsius); CH3Br(3.59 celsius); CH3F(-78 CELSIUS); CH3OH(65 CELSIUS).

CH4 is symmetrical and nonpolar, and as a result has low intramolecular attraction, and boils easily (i.e. at low temperature)

The other compounds are polar to varying degrees. The heaviness of
CH3Br molecules makes them harder to boil than CH3F.

I have no explanation for the high boiling point of CH3OH. There could be some intramolecular hydrogen bonding, as is the case with with water.

To account for the order in the normal boiling points of the resulting compounds, we need to consider the intermolecular forces between the molecules.

In CH4 (methane), the only intermolecular forces present are London dispersion forces, which are relatively weak. As a result, methane has a low boiling point of -161 degrees Celsius.

When we replace one hydrogen atom in CH4 with another atom or group of atoms, we introduce different types of intermolecular forces that affect the boiling points. Let's consider each compound:

1. CH3Br (methyl bromide): In this compound, the hydrogen atom in CH4 is replaced with a bromine atom. Bromine is a larger atom than hydrogen and has higher electron density, leading to stronger London dispersion forces. This increased strength of intermolecular forces results in a higher boiling point of 3.59 degrees Celsius compared to methane.

2. CH3F (methyl fluoride): Fluorine is a smaller atom than hydrogen, and it has higher electronegativity. As a result, the carbon-fluorine bond in CH3F becomes polar, leading to the presence of dipole-dipole interactions in addition to London dispersion forces. These dipole-dipole interactions result in stronger intermolecular forces, increasing the boiling point to -78 degrees Celsius compared to methane.

3. CH3OH (methanol): In this compound, the hydrogen atom in CH4 is replaced with a hydroxyl group (-OH). The hydroxyl group in CH3OH allows for hydrogen bonding between molecules. Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom (in this case, oxygen). The presence of hydrogen bonding significantly increases the intermolecular forces, resulting in a higher boiling point of 65 degrees Celsius compared to the other compounds.

In summary, the order of boiling points from lowest to highest is CH4 (-161°C) < CH3Br (3.59°C) < CH3F (-78°C) < CH3OH (65°C). The boiling points increase as we introduce stronger intermolecular forces, such as larger atoms (increased London dispersion forces), polar bonds (dipole-dipole interactions), and hydrogen bonding.