Explain Zeroth Law of Thermodynamics

Aug 26, 2022, 16:45 IST

Zeroth Law of Thermodynamics

The zeroth law of thermodynamics states that “the two systems are in thermal equilibrium with a third system separately than they are also in thermal equilibrium with each other.”

First Law of Thermodynamics

The first law of thermodynamics is also known as the law of conservation of energy. “The total energy of the universe (system + surroundings) remains constant.”

Factors affecting enthalpy of reaction

(i) Physical State of reactant and product

(ii) Allotropic form

(iii) Stoichiometry of reaction

(iv) Temperature

Types of Enthalpy of reactions

(a) Enthalpy of formation:

“The enthalpy change accompanying the formation of one mole of any substance from its element in their most stable physical state under that condition is called its enthalpy of formation.”

(b) Enthalpy of Combustion:

The enthalpy of combustion of a substance is the enthalpy change accompanying complete combustion of one mole of that substance.  

(c) Enthalpy of Neutralization:

“The enthalpy change when one mole of H+ ions from any acid is completely neutralized by one mole of OH– ions from any base in their dilute solution to forms one mole of water is defined as the enthalpy of neutralization.”

(d) Enthalpy of Solution:

“The change in enthalpy when one mole of a solute is dissolved in a specified quantity of a solvent at a given temperature is called enthalpy of solution.”