1.9: Understand that a Pure Substance has a Fixed Melting and Boiling Point, but that a Mixture may Melt or Boil Over a Range of Temperatures

PURE SUBSTANCE: Contains only one substance with no other substances mixed together

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• As all molecules of the same substance have the same melting and boiling point, pure substance has fixed melting and boiling point

MIXTURE: Combination of two or more substances (Elements and / or Compounds) that are not chemically joined together

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• As mixture contains different substances that have different melting and boiling point, they will have range of melting and boiling point