Why does molecular weight affect boiling point?

First there is molecular size. Large molecules have more electrons and nuclei that create van der Waals attractive forces, so their compounds usually have higher boiling points than similar compounds made up of smaller molecules. The attractive forces between the latter group are generally greater.

Why does CH4 have such a low boiling point in comparison to the other molecules?

Methane has a low boiling point because it has very weak intermolecular forces of attraction.

Why does chloromethane have a lower boiling point than bromomethane?

c) Bromomethane has a lot more electrons than chloromethane. Because of the large numbers of electrons in bromine, we would expect a higher boiling point in 3,4-dibromohexane.

Why boiling point of CH4 is lower than SnH4?

The ordering from lowest to highest boiling point is expected to be CH4< SnH4. It all flows from this general principle: as bonds become more polarized, the charges on the atoms become greater, which leads to greater intermolecular attractions, which leads to higher boiling points.

What is the relationship between molecular weight and boiling point?

In the ABSENCE of other intermolecular force, the higher the molecular mass the greater the boiling point.

Why do larger molecules have higher melting boiling points?

In general, the bigger the molecule, the stronger the intermolecular forces, so the higher the melting and boiling points.

Why boiling point of CH4 is higher than NE?

The boiling point of neon is –246 °C while the boiling point of CH4 is –161 °C. This means that methane molecules are more strongly attracted to each other than are neon atoms.

Why boiling point of SnH4 is higher than CH4?

Therefore, CH4 is expected to have the lowest boiling point and SnH4 the highest boiling point. All of these compounds are nonpolar and only have London dispersion forces: the larger the molecule, the larger the dispersion forces and the higher the boiling point.

Why does bromomethane have a higher boiling point than chloroethane?

The boiling point of bromoethane is higher than that of chloroethane because the bond between C and Cl is more polar than the bond between C and Br. Bromoethane has a larger molar mass and the number of electrons is also more and so has a higher boiling point.

Which has higher boiling point chloromethane or bromomethane?

For alkyl halides containing the same alkyl group, the boiling point increases with an increase in the atomic mass of the halogen atom. Since the atomic mass of Br is greater than that of Cl, the boiling point of bromomethane is higher than that of chloromethane.

Why is the boiling point of PH3 higher than CH4?

NH3 is highest because the N-H bonds give it Hydrogen Bonding Intermolecular Forces. PH3 is next highest because it has dipole dipole forces, which are weaker than “hydrogen bonding” CH4 has neither of those.

Why does boiling point decrease with branching?

Weaker intermolecular forces means that less energy is required to separate the molecules of a compound from its liquid surface, thus lowering the boiling point. As branching increases, the surface area decreases and hence the intermolecular forces of attraction which ultimately results in decrease of boiling point.

Do ethers have a higher boiling point than alkanes?

Hence, I expect ethers (which obviously have dipole-dipole interactions) to have higher boiling points (as boiling point ∝ inter-molecular forces) than alkanes (assuming approximately the same molecular mass). But, the experimental data suggests otherwise.

Why does HF have a higher boiling point than water?

This would seem to predict that each individual hydrogen-bonding interaction is weaker, which would support the higher boiling point of water over HF, BUT this is contradicted by the following point. This data from Wikipedia suggests that HF has stronger hydrogen-bonding interactions amongst HF molecules than in water.

Why do longer chain molecules have a higher boiling point?

The reason that longer chain molecules have higher boiling points is that longer chain molecules become wrapped around and enmeshed in each other much like the strands of spaghetti. More energy is needed to separate them than short chain molecules which have only weak forces of attraction for each other.

What happens if the boiling point is below 20oC?

Hint: If the boiling point is below 20oC, then the liquid has already boiled and is a gas. What is the the boiling point trend in terms of the molecular weights of the compounds?