Fusion curve on P-T diagram for all substances possesses the foll

SOLUTION

Fusion is solid to a liquid phase transition.

For water, v” < v’ (Indicating contraction) \(\Rightarrow \;\frac{{dp}}{{dT}} \to - ve\)

For most other substances v” > v’ (expansion) \( \Rightarrow \;\frac{{dp}}{{dT}} \to + ve\)

• The fusion curve has been drawn with a positive slope, which is typically the case.
• The fusion curve of ice/water has a negative slope due to the fact that when ice melt, the molar volume decreases.
• Ice actually melt at a lower temperature at a higher pressure

Therefore, The slope of the curve is positive as well as negative hence, it is actually variable in nature.