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5. Thermodynamics and thermochemistry — Chemistry STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 ScienceChemistry5. Thermodynamics and thermochemistry1 Mark
MCQ
Hess law is based on
  • A
    Law of conservation of mass
  • ✓
    Law of conservation of energy
  • C
    Enthalpy is a state function
  • D
    None of these
✓

Answer

Correct option: B.
Law of conservation of energy
b
The Hess's law states that the total enthalpy change during the complete course of a chemical reaction is the same whether the reaction is made in one step or in several steps. Hess's law is now understood as an expression of the principle of conservation of energy, also expressed in the first law of thermodynamics, and the fact that the enthalpy of a chemical process is independent of the path taken from the initial to the final state (i.e. enthalpy is a state function).

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