CH4 versus CCl4 (Boiling Point)

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CH4 versus CCl4 (Boiling Point)

Postby 405335722 » Thu Dec 05, 2019 2:03 pm

Why does CCl4 have a higher Boiling Point when CH4 has a shorter bond length?

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Re: CH4 versus CCl4 (Boiling Point)

Postby asannajust_1J » Thu Dec 05, 2019 2:05 pm

CCl4 is a much larger molecule, and has more electrons, so it will form more LDF's, which require more energy to break apart.

andrewcj 2C
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Re: CH4 versus CCl4 (Boiling Point)

Postby andrewcj 2C » Thu Dec 05, 2019 2:08 pm

CH4 has weaker London forces than CCl4 because it is smaller and has fewer electrons, which means the intermolecular forces in CH4 are weaker than those in CCl4 since both molecules are nonpolar. This means it takes less energy to break the attractions between molecules in a sample of CH4, resulting in a lower boiling point.

Justin Vayakone 1C
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Re: CH4 versus CCl4 (Boiling Point)

Postby Justin Vayakone 1C » Thu Dec 05, 2019 2:12 pm

When it comes to boiling point, we have to look at the intermolecular forces (e.g. dipole-dipole and london dispersion forces) not the intramolecular strength (like bond strength within a molecule). Since both CH4 and CCl4 are nonpolar, they both only have london dispersion forces for intermolecular forces. What determines the strength of london dispersion forces is the size of the molecules. Cl is larger than H, so CCL4 has the stronger intermolecular forces. With stronger intermolecular forces, it is harder to break apart CCl4 molecules into gas, meaning a higher boiling point.

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