The standard molar enthalpy of formation of diborane, B₂H₁ (g), cannot be determined directly because the compound cannot be prepared by the reaction of boron and hydrogen. It can be calculated from other enthalpy changes, however. The following enthalpy changes can be measured. 4 B(s) + 3 O₂(g) → 2 B₂O3(s) A, H = -2543.8 kJ/mol-rxn H₂(g) + 1/2O2(g) → H₂O(g) A, H = -241.8 kJ/mol-rxn B₂H6 (g) + 3 O₂(g) → B₂O3(g) + 3 H₂O(g) A,H° = -2032.9 kJ/mol-rxn a we will show how these equations can be added together to give the equation for the formation of B₂ H6 (g) from B(s) and H₂(g) in their standard states and determine the enthalpy of formation. The target reaction is 2 B(s) + 3 H₂(g) → B₂ H6 (g) Does Reaction 1 need to be used as is, or reversed? as is reversed Correct The reaction is used as is because B(s) is a reactant in the target reaction and in Reaction 1. b Does Reaction 1 need to be multiplied by a scaler? Choose a scaling number for Reaction 1. Target Reaction: 2 B(s) + 3 H₂(g) → B₂H6 (g) Scaling number:

The standard molar enthalpy of formation of diborane, B₂H₁ (g), cannot be determined directly because the compound cannot be prepared by the reaction of boron and hydrogen. It can be calculated from other enthalpy changes, however. The following enthalpy changes can be measured. 4 B(s) + 3 O₂(g) → 2 B₂O3(s) A, H = -2543.8 kJ/mol-rxn H₂(g) + 1/2O2(g) → H₂O(g) A, H = -241.8 kJ/mol-rxn B₂H6 (g) + 3 O₂(g) → B₂O3(g) + 3 H₂O(g) A,H° = -2032.9 kJ/mol-rxn a we will show how these equations can be added together to give the equation for the formation of B₂ H6 (g) from B(s) and H₂(g) in their standard states and determine the enthalpy of formation. The target reaction is 2 B(s) + 3 H₂(g) → B₂ H6 (g) Does Reaction 1 need to be used as is, or reversed? as is reversed Correct The reaction is used as is because B(s) is a reactant in the target reaction and in Reaction 1. b Does Reaction 1 need to be multiplied by a scaler? Choose a scaling number for Reaction 1. Target Reaction: 2 B(s) + 3 H₂(g) → B₂H6 (g) Scaling number:

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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