CHEM BRAIN

The net enthalpy change in a chemical reaction is same whether it is brought about in two or more different ways in one or several steps. It is known as NUMS2021 

Combustion of Graphite to form CO2, can be done by two ways. Reactions are given below MDCAT2012

\( C + O_2 \Rightarrow CO_2 \  \Delta H = -393.7KJmol^{-1} \)

\( C + \frac{1}{2}O_2 \Rightarrow CO \  \Delta H_1 = ? \)

\( CO + \frac{1}{2}O_2 \Rightarrow CO_2 \  \Delta H_2 = -283KJmol^{-1} \)

Hess law of heat summation includes [AFMC 1992]

Hess's law of constant heat summation in based on
[MP PET 2001]

“The resultant heat change in a reaction is the same whether it takes place in one or several stages.” This statement is called [MP PMT/PET 1988; MP PMT 1989]