High School

If the enthalpy of fusion and enthalpy of vaporization of sodium metal are 2.6 kJ/mol and 98.2 kJ/mol respectively, what is the total enthalpy change when sodium transitions directly from solid to gas?

A. 32.7 kJ/mol
B. 95.6 kJ/mol
C. 100.8 kJ/mol
D. 101.5 kJ/mol

Answer :

Final answer:

The heat processes corresponding to enthalpy changes are derived from the enthalpy of fusion and vaporization of sodium. Option (c) 100.8 kJ/mol appears to be the total heat required to melt and vaporize sodium, combining both enthalpy values.

Explanation:

The question is asking to identify the heat processes corresponding to enthalpy changes for sodium metal. Given the enthalpy of fusion is 2.6 kJ/mol and the enthalpy of vaporization is 98.2 kJ/mol, we can determine that:

  1. (a) 32.7 kJ/mol does not match either the given enthalpy of fusion or vaporization for sodium.
  2. (b) 95.6 kJ/mol is close to but not exactly the enthalpy of vaporization of sodium.
  3. (c) 100.8 kJ/mol is the addition of the enthalpy of fusion and the enthalpy of vaporization, which could be the total heat required to melt and then vaporize one mole of sodium metal.
  4. (d) 101.5 kJ/mol is also close but does not accurately match the known enthalpy values for sodium.

The closest option that makes sense in this context is likely (c) as it represents combined heat requirements for two-phase changes.

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