Question

Illustrate Hess's law with an example.

Answer 1

According to the hess law the heat change or enthalpy change in a chemical reaction remains same either reaction proceed in one step or in several steps.

Example..
Now here if we do this reaction in one step then,
C + o2 _____ co2 + 94 k. Cal

And if we do this process in two steps we will get the same thing
1. C + 1/2 o2 _____ co + 94k.cal
2. Co + 1/2 o2 _____ co2 + 26k.cal
____________________________
C + o2 _____ co2 + 94 k. Cal.

Answer 2

$\huge\mathfrak{A{\textbf{\red{nswer :}}}}$


$\huge\textbf{Hesse's Law :}$

This law states that heat evolved or absorbed in a reaction is same whether reaction takes place in single step or multiple step.

OR

The total amount of heat energy depends upon nature of reactant and product. But independent of path of reaction.

$\textbf{Example :}$

$CH_{4}$ + $2O_{2}$ ---> $CO_{2}\:+\:2H_{2}O$

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