Hess' Law states that the overall enthalpy change of a chemical reaction is independent of the pathway taken. In other words, the total energy absorbed or released in a chemical reaction is the same regardless of the intermediate steps involved. This applies to the reaction C2H4 + H2O -> C2H5OH because the enthalpy change of this reaction can be calculated using the enthalpy changes of other reactions that involve the same reactants and products.
To determine the enthalpy change of this reaction using Hess' Law, we need to break it down into smaller reactions that have known enthalpy changes. For example, we can break it down into the reactions C2H4 -> C2H2 + H2 and C2H2 + H2O -> C2H5OH, both of which have known enthalpy changes. Then, we can add the enthalpy changes of these reactions to calculate the overall enthalpy change of the reaction C2H4 + H2O -> C2H5OH.
Hess' Law is important in chemistry because it allows us to calculate the enthalpy change of a reaction even if we cannot directly measure it. This is especially useful in industries where the energy released or absorbed in a reaction is important, such as in the production of fuels or pharmaceuticals.
No, Hess' Law can only be applied to reactions that are thermodynamically feasible and involve the same reactants and products. Additionally, the enthalpy changes of the intermediate reactions must be known or can be calculated using other known enthalpy changes.
Yes, there are some limitations to using Hess' Law. One limitation is that it assumes the reaction is taking place under standard conditions, meaning at a constant pressure and temperature. It also does not account for any changes in the state of the reactants or products, such as changes in temperature or phase. Additionally, it is only applicable to enthalpy changes and cannot be used to calculate other thermodynamic quantities such as entropy or free energy.