What is the pH of hydrocarbons?

Answer 1

pH is defined as the negative log of the hydrogen ion concentration; concentration is usually expressed in moles per liter. The liter component is nearly always the universal solvent, water. When you add most hydrocarbons to water, it does not mix; it's immiscible. No hydrogen ions are formed, and the pH of the original water remains unchanged.

However, some types of hydrocarbons DO have a hydrogen ion component when mixed with water. For example, consider methanol - CH3OH. The hydorogen attached to the oxygen in the -OH portion of that molecule will occasionally become unattached when methanol is mixed with water, giving methanol a SLIGHTLY more acidic characteristic than pure water. Thus, the more available one or more hydrogen ions are in the hydrocarbon you are considering, the lower the pH. Note, though, that the number of hydrogens in a molecule does not mean that they are all available. Hexane, C6H6, is less acidic than our methanol example, because the hydrogens are less available.

Answer 2

Hydrocarbons do not have a pH as they are nonpolar compounds and do not dissociate in water to release protons. Therefore, they are neither acidic nor basic.