InterviewSolution
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InterviewSolution
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At `25^(@)C`, the following heat of formations are given: `{:("Compound",SO_(2)(g),H_(2)O(l),,),(Delta_(f)H^(Theta)kJmol^(-1),-296.0,-285.0,,):}` For the reactions at `25^(@)C`, `2H_(2)S(g) +Fe(s) rarr FeS_(2)(s) +2H_(2)(g), DeltaH^(Theta) =- 137 kJ mool^(-1)` `H_(2)S(g) +(3)/(2)O_(2)(g) rarr H_(2)O(l) +So_(2)(g),DeltaH^(Theta) =- 562kJ mol^(-1)` Calculate the heat of formation of `H_(2)S(g)` and `FeS_(2)(g)` at `25^(@)C`. |
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Answer» `4C(s)+5H_(2)+SrarrH-overset(H)overset(|)underset(H)underset(|)(C)-overset(H)overset(|)underset(H)underset(|)(C)-S-overset(H)overset(|)underset(H)underset(|)(C)-overset(H)overset(|)underset(H)underset(|)(C)-H` `4C(s)+5H_(2)+2SrarrH-overset(H)overset(|)underset(H)underset(|)(C)-overset(H)overset(|)underset(H)underset(|)(C)-S-S-overset(H)overset(|)underset(H)underset(|)(C)-overset(H)overset(|)underset(H)underset(|)(C)-H` `DeltaH = sum(BE)_(R)-sum(BE)_(P)` a. `-147.2 =` Heat of atomisation of `4C,10H,1S -BE` of `10(C -H), 2(C-S), 2(C-C)` b. `-201.9 =`Heat of atomization of `4C, 10H, 2S - BE of 10(C-H), 2(C-S), 2(C-C), (S-S)` Subtracting equations (i) from (ii), we get `-201.9 +14.2 =`Heat of atomisation of `1S -BE of (S-S)` `= 22.8 kJ -BE of (S-S)` `BE of (S-S) = 277.5 kJ` |
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