Germain Henri Hess was a Swiss chemist born in 1802 who studied heat in chemical reactions and laid the foundation for thermochemistry. Hess's law states that the heat evolved or absorbed in a chemical reaction depends only on the chemical identities of the initial and final substances and is independent of the pathway between them. Thermochemistry deals with the thermal changes that accompany physical and chemical transformations and aims to determine energy absorption or emission and develop methods to calculate these thermal changes experimentally, such as determining heats of formation, transition, and reaction.

1. BY MUHAMMAD MUJEEB
MUHAMMAD NABEEL

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

4.  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.

5.  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.

8.  The heat of transition of one allotropic form
to another allotropic form is called enthalpy
of transition.

9.  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.