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Heat of combustion `DeltaH^(@)` for `C(s),H_(2)(g)` and `CH_(4)(g)` are `94, -68` and `-213Kcal//mol` . Then `DeltaH^(@)` for `C(s)+2H_(2)(g)rarrDeltaCH_(4)(g)` isA. `-17 kcal`B. `-111 kcal`C. `-170 kcal`D. `85 kcal` |
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Answer» Correct Answer - A `(i) C(s)+2H_(2)(g)toCH_(4)(g)` `(ii) C(s)+O_(2)(g)toCO_(2)(g)` , `DeltaH=-94 kcal mol^(-1)` `(iii) H_(2)(g)+(1)/(2)O_(2)(g)toH_(2)O(l)`, `DeltaH=-68kcal mol^(-1)` `(iv) CH_(4)+3//2O_(2)toCO_(2)+2H_(2)O`, `DeltaH=-213 kcal mol^(-1)` To obtain eqn. `(i)` operate `(ii)+2xx(iii)-(iv)` `:. DeltaH=-94+2(-68)-(-213)` `=-94-136+213` `=-230+213=-17 kcal` |
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