Respuesta :
δHrxn = ΣδΗ(bond breaking) - ΣδΗ(bond making)
Bond enthalpies,
N ≡ N ⇒ 945 kJ mol⁻¹
N - Cl ⇒ 192 kJ mol⁻¹
Cl - Cl⇒ 242 kJ mol⁻¹
According to the balanced equation,
ΣδΗ(bond breaking) = N ≡ N x 1 + Cl - Cl x 3
= 945 + 3(242)
= 1671 kJ mol⁻¹
ΣδΗ(bond making) = N - Cl x 3 x 2
= 192 x 6
= 1152 kJ mol⁻¹
δHrxn = ΣδΗ(bond breaking) - ΣδΗ(bond making)
= 1671 kJ mol⁻¹ - 1152 kJ mol⁻¹
= 519 kJ mol⁻¹
Bond enthalpies,
N ≡ N ⇒ 945 kJ mol⁻¹
N - Cl ⇒ 192 kJ mol⁻¹
Cl - Cl⇒ 242 kJ mol⁻¹
According to the balanced equation,
ΣδΗ(bond breaking) = N ≡ N x 1 + Cl - Cl x 3
= 945 + 3(242)
= 1671 kJ mol⁻¹
ΣδΗ(bond making) = N - Cl x 3 x 2
= 192 x 6
= 1152 kJ mol⁻¹
δHrxn = ΣδΗ(bond breaking) - ΣδΗ(bond making)
= 1671 kJ mol⁻¹ - 1152 kJ mol⁻¹
= 519 kJ mol⁻¹
The value of [tex]\Delta {H_{{\text{reaction}}}}[/tex] of the reaction [tex]{{\text{N}}_{\text{2}}}\left( g \right) + 3{\text{C}}{{\text{l}}_2}\left( g \right) \to 2{\text{NC}}{{\text{l}}_3}\left( g \right)[/tex] is [tex]\boxed{519\;{\text{kJ/mol}}}[/tex].
Further explanation:
Heat of reaction:
The heat released or absorbed in a chemical reaction due to the difference in the bond energies (BE) of reactants and products in the reaction is known as the heat of reaction. It is represented by[tex]\Delta {H_{{\text{reaction}}}}[/tex].
The heat of reaction [tex]\left( {\Delta {H_{{\text{reaction}}}}} \right)[/tex]can have two values:
Case I: If the reaction is endothermic, more energy needs to be supplied to the system than that released by it. So [tex]\Delta {H_{{\text{reaction}}}}[/tex] comes out to be positive.
Case II: If the reaction is exothermic, more energy is released by the system than that supplied to it. So [tex]\Delta {H_{{\text{reaction}}}}[/tex] comes out to be negative.
The formula to calculate the heat of reaction is,
[tex]\boxed{\Delta {H_{{\text{reaction}}}} = \sum {\text{B}}{{\text{E}}_{{\text{reactant bond broken}}}} - \sum {\text{B}}{{\text{E}}_{{\text{product bond formed}}}}}[/tex]
Here,
[tex]\Delta {H_{{\text{reaction}}}}[/tex] is the heat of reaction.
[tex]{\text{B}}{{\text{E}}_{{\text{product bond formed}}}}[/tex] is the bond energy of bond formation in products.
[tex]{\text{B}}{{\text{E}}_{{\text{reactant bond broken}}}}[/tex] is the bond energy of bond breakage in reactants.
The given reaction occurs as follows:
[tex]{{\text{N}}_{\text{2}}}\left( g \right) + 3{\text{C}}{{\text{l}}_2}\left( g \right) \to 2{\text{NC}}{{\text{l}}_3}\left( g \right)[/tex]
The number of broken bonds is 1 N-N triple bond and 3 Cl-Cl bonds.
The number of bonds formed is 6 N-Cl bonds.
The formula to calculate the enthalpy of the given reaction is as follows:
[tex]\Delta {H_{{\text{reaction}}}} = \left[ {\left( {1{\text{B}}{{\text{E}}_{{\text{N}} - {\text{N}}}} + 3{\text{B}}{{\text{E}}_{{\text{Cl}} - {\text{Cl}}}}} \right) - \left( {{\text{6B}}{{\text{E}}_{{\text{N}} - {\text{Cl}}}}} \right)} \right][/tex] …… (1)
The bond energy of N-N triple bond is 945 kJ/mol.
The bond energy of N-Cl bond is 192 kJ/mol.
The bond energy of Cl-Cl bond is 242 kJ/mol.
Substitute 945 kJ/mol for[tex]{\text{B}}{{\text{E}}_{{\text{N}} - {\text{N}}}}[/tex], 192 kJ/mol for[tex]{\text{B}}{{\text{E}}_{{\text{N}} - {\text{Cl}}}}[/tex], 242 kJ/mol for[tex]{\text{B}}{{\text{E}}_{{\text{Cl}} - {\text{Cl}}}}[/tex], in equation (1).
[tex]\Delta {H_{{\text{reaction}}}}&=\left[ {\left( {\left( {{\text{1 mol}}} \right)\left( {945\;{\text{kJ/mol}}} \right) + \left( {{\text{3 mol}}} \right)\left( {242\;{\text{kJ/mol}}} \right)} \right) - \left( {{\text{6 mol}}} \right)\left( {192\;{\text{kJ/mol}}} \right)} \right]\\\begin{aligned}&=\left[{\left({94{\text{5 kJ/mol}} + 72{\text{6 kJ/mol}}} \right) - 115{\text{2 kJ/mol}}} \right]\\&=\left[{167{\text{1 kJ/mol}} - 115{\text{2 kJ/mol}}} \right] \\ \end{aligned}[/tex]
Learn more:
1. Calculate the enthalpy change using Hess’s Law: https://brainly.com/question/11293201
2. Find the enthalpy of decomposition of 1 mole of MgO: https://brainly.com/question/2416245
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Thermodynamics
Keywords: N2, Cl2, NCl3, bond energies, N-Cl bond, N-N bond, Cl-Cl bond, 519 kJ/mol, heat of reaction, released, absorbed, exothermic, endothermic, positive, negative.
