Calculate the enthalpy change for the reactionH2-g- Br2-g-2HBr-g-Given -Bond enthalpy of H mdash-H - 435 kJ mol-1Bond enthalpy of Br mdash-Br - 192 kJ mol-1Bond enthalpy of H mdash-Br - 364 kJ mol-1

H2(g)+ Br2 nbsp;(g) rarr; nbsp;2HBr(g) Given : Bond enthalpy of H mdash;H = 435 kJ mol 1 Bond enthalpy of Br mdash;Br = 192 kJ mol 1 Bond entha ...

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Standard VIII

Chemistry

Characteristics of Chemical Reaction

Calculate the...

Question

Calculate the enthalpy change for the reaction
H2(g)+ Br2(g)2HBr(g)Given :Bond enthalpy of H—H = 435 kJ mol-1Bond enthalpy of Br—Br = 192 kJ mol-1Bond enthalpy of H—Br = 364 kJ mol-1

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Solution

H₂(g)+ Br₂ (g) → 2HBr(g)

Given :
Bond enthalpy of H—H = 435 kJ mol^-1
Bond enthalpy of Br—Br = 192 kJ mol^-1
Bond enthalpy of H—Br = 364 kJ mol^-1

Reaction for the given bond enthalpies are

H₂(g) →2H(g) ∆H= 435 kJmol^-1 (energy required to break the bond. Hence positive. )
Br₂(g) → 2Br(g) ∆H= 192 kJmol^-1
H(g)+Br(g) →HBr(g) ∆H= -364 kJmol^-1(energy released due to bond formation. Hence taken negative)

Multiply Third equation by two and add all three question to get to the equation
H₂(g)+Br₂(g)-->2HBr(g)

Hence,enthalpy change for the reaction
∆H = 435+192+2(-364)
= -101 kJ/mol^-1

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Calculate the enthalpy change for the reactionH2(g)+ Br2(g)2HBr(g)Given :Bond enthalpy of H—H = 435 kJ mol-1Bond enthalpy of Br—Br = 192 kJ mol-1Bond enthalpy of H—Br = 364 kJ mol-1

Calculate the enthalpy change for the reaction
H2(g)+ Br2(g)2HBr(g)Given :Bond enthalpy of H—H = 435 kJ mol-1Bond enthalpy of Br—Br = 192 kJ mol-1Bond enthalpy of H—Br = 364 kJ mol-1