Question

Review Constants Periodic Tab Enthalpy (H) is a state function, which means the enthalpy of a given chemical reaction is independent of the path taken from the initial to final states for that chemical reaction. Enthalpy Change (AI) is a measure of the energy change of a system that does virtually no Calculating Reaction Enthalpies Using Hess's Law Follow the steps below and use the information provided on the left to find the A Hm for the following process: Overall Reaction : 2D + A+2B AH. - ? kJ Given: A AH value written at the end of a balanced equation represents the heat change that occurs when the quantities reacting are equal to the coefficients in the balanced equation Enthalpy of Reaction ( A m ) is equal to the heat gained or lost by the reaction at constant pressure AH qraim (at constant pressure) C Reaction 1: D Reaction 2: A+2B AH AH 2 0 2.0 kJ 10.0 kJ The questions that follow will have you manipulate Reactions 1 and 2 so that the sum of the individual reactions will result in the overall reaction. Hess's Law states that if a reaction process takes place in a series of steps, the enthalpy of reaction, AH.. will equal the sum of the enthalpy changes for the individual steps in that reaction process • When you multiply an entire reaction by a number, you must also multiply AH by the same number. . When you reverse an entire reaction, you must also change the sign of AH Part A. Comparing Reaction 1 to the overall reaction . The amount of heat released or absorbed depends directly on the amount of substance that reacts, therefore, His an extensive property to the AH value for 2 moles of a substance will be twice the AH value for 1 mole of the substance) The overal reaction has two times the moles of D in the balanced equation. This means that Reaction doubled to achieve the overall reaction. What is the new AH, once you have double Reaction 17 will have to be (new) Reaction 1: 2D 2 C (new)AH, • the reaction is run in reverse the sign, but not the magnitude of AH will change . If a reaction releases a certain quantity of heat it will absorb the same amount of that the reverse reaction were to coun) Submit Rest A Part B. Comparing Reaction 2 to the overall reaction

Answer 1

The amount of hest released or absorbed depends directly on the amount of substance that reets, therefore AH value for anoles of o will be twice the al value of Imole of the substance. 2D + 2C (new) 14, - 2x an, (old) = 2x2.06f ²4.0kg