In this worksheet, we will practice explaining differences in the viscosities of liquids based on the relative energies of their intermolecular forces.
Under standard conditions, -butanol has a surface tension of 24.3 mJ/m2 and a viscosity of 2.593 MPa⋅s, while tert-butanol has a surface tension of 19.2 mJ/m2 and a viscosity of 3.35 MPa⋅s. The structures of the compounds are shown below.
Explain the difference between the surface tensions of the two liquids.
- AMolecules of -butanol are more linear so a larger transient dipole can develop, producing stronger dispersion forces.
- BThe greater branching in tert-butanol reduces the strength of each hydrogen bond.
- CMolecules of tert-butanol have a smaller dipole moment so form weaker dipole-dipole attractions.
- DMolecules of -butanol are more linear so can pack more closely together.
- EMolecules of tert-butanol are more symmetrical so form more ordered arrangements at the liquid surface.
Explain the difference between the viscosities of the two liquids.
- AMolecules of -butanol are more linear so flow past each other more easily.
- BMolecules of tert-butanol form crystalline species which flow less easily.
- CMolecules of -butanol have a smaller dipole moment so form weaker dipole-dipole attractions.
- DThe greater branching in tert-butanol increases the strength of each hydrogen bond.
- EThe more symmetrical vibrations of tert-butanol produce a stronger resistance to the liquid flow.