Compare the structure and composition of n-pentane and octadecane and explain why octadecane has the higher viscosity.

Octadecane is more viscous than n-pentane because:

• the shape of octadecane molecules is irregular and asymmetrical. This results in greater entanglement of octadecane molecules.
• there are more intermolecular forces between an octadecane molecule and its neighbors than between a n-pentane molecule and its neighbors.

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