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States of matter

Learn about melting, vaporization, and states of matter in this educational guide. Explore the differences between freezing and melting points, the impact of impurities on melting points, and the apparatus used for measuring melting points.

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States of matter

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  1. Melting Vaporization States of matter

  2. Objectives • Explain :- • Melting • The Liquid State • Vaporisation

  3. What states exist at the point of melting?

  4. At the melting point the solid and liquid phase exist in equilibrium. • The melting point of a solid is the temperature range at which it changes state from solid to liquid • http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/enm1s3_4.swf Mc Graw Hill

  5. What’s the difference between freezing and melting point

  6. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point • When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice", i.e. the melting point • For most substances, melting and freezing points are approximately equal • A pure organic compound usually melts over a range of two degrees or less. • If the melting point of a pure compound is within a degree of the value found a lab handbook it is presumed to be pure.

  7. Impurities and the Melting point • A sample is impure if it has a melting point range that is lower and /or wider than that the literature value. • More impurities increase this effect.

  8. Melting point Apparatus See handout

  9. Changes in the State of Matter • http://hogan.chem.lsu.edu/matter/chap26/animate3/an26_035.mov Louisiana State University • http://mutuslab.cs.uwindsor.ca/schurko/animations/waterphases/status_water.htm Iowa State University

  10. Vaporisation • Vaporization of an element or compound is a phase transition from the liquid phase to gas phase. There are two types of vaporization: evaporation and boiling. • Evaporation is a phase transition from the liquid phase to gas phase that occurs at temperatures below the boiling temperature at a given pressure. Note: evaporation usually occurs on the surface. • Boiling is a phase transition from the liquid phase to gas phase that occurs at or above the temperature the boiling temperature. Note boiling occurs below the surface. • http://www.chm.davidson.edu/ronutt/che115/Phase/Phase.htm

  11. The End

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