How is Hess's law used to measure enthalpy of a desired reaction?A.Intermediate equations with known enthalpies are added together.B.The enthalpy from the final equation in a series of reactions is used.C.The enthalpy is determined from the enthalpy of similar reactions.D.The enthalpy is obtained from the enthalpy of an intermediate step.
Question
How is Hess's law used to measure enthalpy of a desired reaction?A.Intermediate equations with known enthalpies are added together.B.The enthalpy from the final equation in a series of reactions is used.C.The enthalpy is determined from the enthalpy of similar reactions.D.The enthalpy is obtained from the enthalpy of an intermediate step.
Solution
Hess's law is used to measure the enthalpy of a desired reaction through the following steps:
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Identify the initial and final states of the reaction you are interested in. This is your target equation.
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Find intermediate reactions that, when added together, will give you the target equation. These reactions should have known enthalpies. This is the principle of Hess's law, which states that the total enthalpy change of a reaction is the sum of the enthalpy changes of the intermediate reactions, regardless of the path taken.
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Add together the enthalpies of these intermediate reactions. The sum will give you the enthalpy of the desired reaction.
So, the correct answer to your question is A. Intermediate equations with known enthalpies are added together.
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How is Hess's law used to calculate the enthalpy of a reaction?A.The desired enthalpy is obtained through adding intermediate reactions together.B.The enthalpy is obtained from the difference in final and initial reactions in a path.C.The final equation in a reaction path provides the enthalpy for the desired reaction.D.Enthalpies from similar equations are substituted for unknown reaction enthalpies.SUBMITarrow_backPREVIOUS
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How can an unknown Hreaction be determined using Hess's law?A.The free energy of the reaction is used to determine the H for the reaction.B.The unknown Hreaction is determined after the reaction is run in a calorimeter.C.The reaction is repeated at different temperatures to determine the Hreaction.D.Enthalpies from reaction steps are added to determine an unknown Hreaction.
Using Hess’s Law, the enthalpy of any reaction can be determined as long as… Group of answer choicesthe reaction has been performed in a calorimeterthe enthalpies are added for any set of reactions that add to give the reaction of interestthe reaction does not involve any change in colorno energy is lost in the reaction
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