C_(2)H_(6(g)) + 3.5 O_(2(g)) rarr 2CO_(2(g)) + 3H_(2)O_((g)) Delta S_("vap") (H_(2)O,l) = x_(1) " cal" K^(-1) (boiling point is T_(1)) Delta H_(f) (H_(2)O, l) = x_(2), Delta H_(f) (CO_(2)) = x_(3), Delta H_(f) (C_(2)H_(6)) = x_(4) Hence Delta H for the reaction is

C_(2)H_(6(g)) + 3.5 O_(2(g)) rarr 2CO_(2(g)) + 3H_(2)O_((g)) Delta S_

1.	C_(2)H_(6(g)) + 3.5 O_(2(g)) rarr 2CO_(2(g)) + 3H_(2)O_((g)) Delta S_("vap") (H_(2)O,l) = x_(1) " cal" K^(-1) (boiling point is T_(1)) Delta H_(f) (H_(2)O, l) = x_(2), Delta H_(f) (CO_(2)) = x_(3), Delta H_(f) (C_(2)H_(6)) = x_(4) Hence Delta H for the reaction is
Answer» `2x_(3) + 3x_(2) - x_(4)` `2x_(3) + 3x_(2) - x_(4) + 3x_(1) T_(1)` `2x_(3) + 3x_(2) - x_(4) - 3x_(1) T_(1)` `x_(1) T_(1) + X_(2) + X_(3) - x_(4)` Solution :`DELTA H_("vap") (H_(2)O) = Delta S xx T_(BP) = x_(1)T_(1)` `Delta H = 2DELTA H_(f_(CO_(2)))- Delta H_(f_(C_(2)H_(6)))` `2x_(3) + 3(x_(2) + x_(1) T_(1)) - x_(4)`