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Question: Answered & Verified by Expert
If x1,x2 and x3 are enthalpies of H-H,O=O and O-H bonds respectively, and x4 is the enthalpy of vaporization of water, estimate the standard enthalpy of combustion of hydrogen.
ChemistryThermodynamics (C)NEET
Options:
  • A x1+x22-2x3+x4
  • B x1+x22-2x3-x4
  • C x1+x22-x3+x4
  • D 2x3-x1-x22-x4
Solution:
1707 Upvotes Verified Answer
The correct answer is: x1+x22-2x3-x4
H2(g)+12O2(g)H2O(l) …(i)
H2(g)2H(g); ΔH=x1
O2(g)2O(g); ΔH=x2
H2O(l)H2O(g); ΔH=x4
H2O(g)2H(g)+O(g); ΔH=2x3
Using all four, we (find) (i)
x1+x22-x4-2x3

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