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Diborane is potential rocket fuel which undergoes combustion according to the reaction, B_(2)H_(6(g))+3O_(2(g))rarr B_(2)O_(3(s))+3H_(2)O_((g))from the following data, calculate the enthalpy change for the combustion of diborane , {:(2B_((s))+(3)/(2)O_(2(g))rarrB_(2)O_(3(g)),,,Delta H=-1273 kJ),(H_(2(g))+(1)/(2)O_(2(g))rarr H_(2)O_((l)),,,Delta H=-28 kJ),(""H_(2)O_((l))rarr H_(2)O_((g)),,,Delta H=44 kJ),(2B_((S))+3H_(2)(g)rarr B_(2)H_(6(g)),,,Delta H=36 kJ):} |
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Answer» Solution :`B_(2)H_(6(g))+3O_(2(g))rarr B_(2)O_(3(g))+3H_(2)O_((g)) "" DELTA H = ?` MULTIPLY equation (2) and (3) by 3, add equation (1), (2) and (3) and then subtract equation (4) from that `{:(""2B_((s))+(3)/(2)O_(2(g))rarr B_(2)O_(3(g)) "," Delta H=-1273 kJ mol^(-1) "".......(1)),(""3H_(2(g))+(3)/(2)O_(2(g))rarr 3H_(2)O_((L)) "," Delta H =-286xx3"".......(2)),(ul(""3H_(2)O_((l))rarr 3H_(2)O_((g)) " ," Delta H=-44xx3 "".......(3)"")),("On ADDITION " 2B_((s))+3H_(2(g))+3O_(2(g))rarr B_(2)O_(3(g))+3H_(2)O_((g)) , Delta H=-1999),(ul(""2B_((s))+3H_(2(g))rarr B_(2)H_(6(g)) , Delta = 36"")),("On subtraction " B_(2)H_(6(g))+3O_(2(g))rarr B_(2)O_(3(g))+3H_(2)O_((g))" ,"Delta H=-2035 kJ mol^(-1)):}` |
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