Why does the viscosity of alkanes increase with chain length?

Why does the viscosity of alkanes increase with chain length?

As the alkane molecules get larger the chains can align themselves in such arrangements that the intermolecular forces can operate along the whole length of the molecule. The increase in viscosity is also due to the increase in intermolecular forces between molecules of increasing size.

What happens as you increase the chain length of an alkane?

For example, as the chain length increases, their boiling point increases. The general formula means that the number of hydrogen atoms in an alkane is double the number of carbon atoms, plus two. This means that their carbon atoms are joined to each other by single bonds.

How does the length of the hydrocarbon affect the viscosity?

As you go up the fractionating column, the hydrocarbon molecules get smaller and have: lower boiling points. lower viscosity (they flow more easily) higher flammability (they ignite more easily)

Why do alkanes get thicker and less runny as the length of the carbon chain increases?

As the carbon chain increases in length, there are more intermolecular forces holding molecules together. This means that the substance will become denser as the carbon chain increases.

Why do straight chains have higher boiling points?

Straight chain compounds have large size and hence have large polarizability and have strong London dispersion forces hence high boiling points while branched compounds have compact structure and hence have low polarizability and have low boiling points.

Why chain length increases boiling point?

As the length of an alkane chain increases, the boiling point increases. This is because there are more points of contact with each adjacent molecule. This means there are stronger induced dipole to dipole forces between adjacent molecules.

How does viscosity change as the length of the hydrocarbon chain increases?

As the number of carbon atoms increases in hydrocarbons, the viscosity gradually increases – this is due to the intermolecular forces of attraction being greater for longer chains and a higher chance of chains entangling.

Does viscosity increase with size of molecule?

Smaller molecules slide past each other more easily than larger molecules do. Larger molecules also have stronger intermolecular forces, such as London Forces, which connect them to one another with greater power. This inhibits molecular flow, resulting in higher viscosity.

Why does hydrocarbon boiling point increase with longer chain length?

Why straight chain alkanes have higher boiling points than branched chain alkanes?

Why do straight chain alkanes have higher melting points?

Summary; Alkanes are non-polar molecules containing only carbon and hydrogen atoms, and only single bonds. Thus, the interactions between molecules are the relatively weak van der Waals (London/Dispersion) forces, which increase as the surface area/size of the molecule increases.