Hass\'s law

1.	Hass\'s law
Answer» This law states that the amount of heat evolved or absorbed in a process, including a chemical change is the same whether the process takes place in one or several steps.Suppose in a process the system changes from state A to state B in one step and the heat exchanged in this change is q. Now suppose the system changes from state A to state B in three steps involving a change from A to C, C to D and finally from D to B. If q1, q2\xa0and q\xad3\xa0are the heats exchanged in the first, second and third step, respectively then according to Hess’s lawq1\xa0+ q2\xa0+ q3\xa0= qHess’s law is simply a corollary of the first law of thermodynamics. It implies that enthalpy change of a reaction depends on the initial and final state and is independent of the manner by which the change is brought about.

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