The boiling points, surface tensions, and viscosities of water and several alcohols are as shown below: (a) From ethanol to propanol to \(n\) -butanol the boiling points, surface tensions, and viscosities all increase. What is the reason for this increase? (b) How do you explain the fact that propanol and ethylene glycol have similar molecular weights ( 60 versus \(62 \mathrm{u}\) ), yet the viscosity of ethylene glycol is more than 10 times larger than propanol? (c) How do you explain the fact that water has the highest surface tension but the lowest viscosity?

(a) The boiling points, surface tensions, and viscosities of ethanol, propanol, and n-butanol increase due to the increasing size and surface area of their molecules, resulting in greater van der Waals forces between molecules as the carbon chain length increases. (b) Despite having similar molecular weights, ethylene glycol has higher viscosity than propanol because of its molecular structure with two hydroxyl (-OH) groups, allowing it to form stronger intermolecular forces through more hydrogen bonding compared to propanol. (c) Water has the highest surface tension due to its extensive hydrogen bonding between molecules, but the lowest viscosity because its smaller molecular size leads to lesser internal friction and van der Waals forces compared to alcohols.