Complex sentence: Fractional distillation is the separation of a mixture into its component parts, or fractions, chemical compounds are separated by heating them to a temperature at which one or more fractions of the compound will vaporize.
Split into simpler sentences: Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the compound will vaporize.