Can someone help me answer this question about melting of crystalline solids? Thanks!

  1. Which graph shows the melting of crystalline solids? Explain your reasoning.
  2. What type of solid does the other graph show? Explain.

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1 Answer
anor277
Jan 17, 2018

The rightmost graph (as we face the page) is the one that specifies the melting point of a crystalline solid....

Explanation:

When a material reaches fusion point, there is a phase equilibrium...

#"solid "rightleftharpoons" liquid"#

While the solid and liquid phases are BOTH at the same temperature, energy has to be supplied to effect the phase transition....the so-called #"latent heat of fusion"#...which represents the energy required to break the solid-solid bonds.

Crystalline materials tend to have sharply defined melting points, and this is one reason we quote melting points as a means to identify unknown organic derivatives.

The leftmost graph represents the heating of a gas or a liquid that is well-below its boiling point.... Just noticed that both graphs are labelled #"Graph B...."#, you sure fooled me!

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