Question

   The Dulong and Petit empirical relationship for the product of atomic mass and specific heat, (Mm)(Cp) = 25, indicates that the specific heat is inversely proportional to the atomic mass or proportional to the number of moles of particles as with colligative properties.

a. For at least four metals, test the Dulong and Petit relationship. Is it accurate?

Answer 1

Mm = molar mass

Cp = specific hat capacity

so...

For:

a)

Aluminium

Cp = 0.91

Mm = 26.981539

Formula = Mm/Cp = 26.981539*0.91 = 24.55

fails

b)

Iron

Cp = 0.45

Mm = 55.8450

Formula = Mm/Cp = 55.8450*0.45 = 25.13

c)

Zinc

Cp = 0.39

Mm = 65.38

Formula = Mm/Cp = 65.38*0.39 = 25.4982

d)

Chromium

Cp = 0.46

Mm = 51.9961

Formula = Mm/Cp =0.46*51.9961 = 23.91

It is very consistent, for a rough calculation it is fine...

But nowadays it will be easier to simply look for Cp valu or Mm in databases/books/internet