Hess’s law of constant heat summation

hess's Law

1. Hess’s law of constant heat summation BY MUHAMMAD MUJEEB MUHAMMAD NABEEL

2. CONTENT: HISTORY. HESS’S LAW. EXAMPLES . APPLICATION .{ with Examples } Determination of heat of formation. Determination of Enthalpy of transition. Determination of Standard heat of reaction

3. HISTORY: GERMAIN HENRICH HESS’S WAS BORN ON AUGUST 07 1802 IN GENEVA SWITZERLAND. After practicing medicine for several year in russia . Has become professor of chemistry in 1830. His studies of heat in chemical reaction formed the foundation of thermochemistry .

4. Thermochemistry : Thermochemistry is a branch of chemistry which deals with the thermal changes accompaying physical & chemical transformation. Aim of chemistry is not only determine he absorption or emmission of energy but also to developed the method for calculating these thermal changes with experiments.

5. Statement of Hess’s law :

6. APPLICATIONS OF HESS’S LAW Determination of heat of formation:

7. DETERMINATION OF ENTHALPY OF TRANISITION : The heat of transition of one allotropic form to another allotropic form is called enthalpy of transition.

8. DETERMINATION OF STANDARAD HEAT OF REACTION : The standard enthalpy of reaction is the change in enthalpy that occur in a system when one mole of matter is transferred by a chemical reaction under standard condition ; such as temperature and pressure.