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# Hess's Law and Enthalpy Change

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1. Attachment 544041544043
Why is my cycle wrong? The answer doesn't match if I use this cycle.
Thanks for any help in advance!
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2. (Original post by 123PC)

Attachment 544041544043
Why is my cycle wrong? The answer doesn't match if I use this cycle.
Thanks for any help in advance!
Can't read it without getting a crick in my neck ... so I won't
3. (Original post by charco)
Can't read it without getting a crick in my neck ... so I won't
Rotated version!
4. (Original post by 123PC)
Rotated version!
Write out the relevant equations:

equation 1: S8(s) + 8O2(g) --> 8SO2(g) ............ -2376 kJ
equation 2: S8(s) --> 8S(g) ................................ ............................ +2232 kJ
equation 3:O2(g) --> 2O(g) ................................ ............................ +496 kJ

equation 1 can go via the elements in single atomic state (gaseous)

S8(s) + 8O2(g) --> 8S + 16O ................ +2232 + 8(496) = 6200 kJ

Then to go to 8SO2 is -16 x S=O bond enthalpy

So

-2376 = 6200 - 16(S=O)

rearrange

16(S=O) = 6200 + 2376 = 8576

Hence S=O bond enthalpy = 8576/16 = 536 kJ
5. (Original post by charco)
Write out the relevant equations:

equation 1: S8(s) + 8O2(g) --> 8SO2(g) ............ -2376 kJ
equation 2: S8(s) --> 8S(g) ................................ ............................ +2232 kJ
equation 3:O2(g) --> 2O(g) ................................ ............................ +496 kJ

equation 1 can go via the elements in single atomic state (gaseous)

S8(s) + 8O2(g) --> 8S + 16O ................ +2232 + 8(496) = 6200 kJ

Then to go to 8SO2 is -16 x S=O bond enthalpy

So

-2376 = 6200 - 16(S=O)

rearrange

16(S=O) = 6200 + 2376 = 8576

Hence S=O bond enthalpy = 8576/16 = 536 kJ
Thanks!

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