Which of the following is the best definition of Hess' Law?
A. Heat evolved in a given process can be expressed as the sum of the heats of several processes that, when added, yield the process of interest.
B. The enthalpy of a process is the difference between the enthalpy of the products and the enthalpy of the reactants.
C. Since enthalpy is a state function, it will be different if a reaction takes place in one step or a series of steps.
D. Heat is always released by the decomposition of 1 mole of a compound into its constitute elements.
E. At constant pressure the enthalpy change of a reaction is equal to the heat change of a reaction.
A i think i put A and i got it right for my lab webwork
Congratulations on getting the correct answer for your lab. Hess' Law is a fundamental principle in thermodynamics that deals with the calculation of enthalpy changes in chemical reactions. It allows us to determine the enthalpy change of a reaction by using the enthalpy changes of other related reactions.
To understand why option A is the best definition of Hess' Law, let's go through the other options:
B. The definition in option B describes the concept of enthalpy change, but it doesn't specifically mention Hess' Law or the fact that enthalpy changes can be added together to yield the overall enthalpy change.
C. Option C mentions that enthalpy is a state function, which is true, but it doesn't explicitly explain the concept of Hess' Law.
D. The statement in option D is a specific case of an enthalpy change, namely the decomposition of a compound into its elements. It doesn't provide a general definition of Hess' Law.
E. Option E describes the relationship between enthalpy change and heat change, but it doesn't specifically mention the principle of combining multiple reactions to determine the overall enthalpy change.
Therefore, the best definition of Hess' Law is indeed option A. It states that the heat evolved in a given process can be expressed as the sum of the heats of several processes that, when added, yield the process of interest. This definition highlights the key concept of Hess' Law, which is the ability to combine multiple reactions to determine the overall enthalpy change.