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):}`

Explanation

`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)):}`