question_answer

Diborane is a potential rocket fuel which undergoes combustion according to the equation \[{{B}_{2}}{{H}_{6}}\left( g \right)+3{{O}_{2}}\left( s \right)\xrightarrow{{}}{{B}_{2}}{{O}_{3}}\left( s \right)+3{{H}_{2}}O\left( g \right)\]Calculate the enthalpy change for the combustion of diborane. Given

(i) \[2B(s)+\frac{3}{2}{{O}_{2}}(g)\xrightarrow{{}}{{B}_{2}}{{O}_{3}}(s);\]\[\Delta H=-1273\text{ }kJ\]per mol

(ii) \[{{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}{{H}_{2}}O(l);\]\[\Delta H=-286\text{ }kJ\] per mol

(iii) \[{{H}_{2}}O\left( l \right)\xrightarrow{{}}{{H}_{2}}O\left( g \right);\]\[\Delta H=44\text{ }kJ\]per mol

(iv) \[2B(s)+3{{H}_{2}}(g)\xrightarrow{{}}{{B}_{2}}{{H}_{6}}(g);\]\[\Delta H=36\text{ }kJ\]per mol

A) \[+2035\text{ }kJ\]per mol

B)   \[-2035\text{ }kJ\] per mol

C) \[+2167kJ\] per mol       

D) \[-2167kJ\] per mol