Each component in a mixture contributes a fraction to the total number of moles in the mixture. This fraction is called the fraction of the component. In a mixture of gases, this fraction is proportional to the pressure for each gas present.

Each component in a mixture contributes a fraction to the total number of moles in the mixture. This fraction is called the _mole_ fraction of the component. In a mixture of gases, this fraction is proportional to the _mole_ pressure for each gas present.

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.