Given the combustion of silane... #SiH_4(g)+2O_2(g)rarrSiO2(s)+2H_2O(g); DeltaH=−1429⋅kJ⋅mol^(−1)#.. How much heat will evolve given combustion of #15.7*g# quantity?

1 Answer
Nov 28, 2016

Answer:

Approx. #700*kJ#

Explanation:

Thermochemical reactions ALWAYS quote enthalpy input/output PER MOLE OF REACTION AS WRITTEN:

#SiH_4(g) + 2O_2(g) rarr SiO_2(s) + 2H_2O(g)# #DeltaH=-1429*kJ*mol^-1#.

That is #-1429*kJ*mol^-1# of energy are involved when #1*mol#, #33*g# of silane are combusted to give stoichiometric silicon oxide, and water.

And thus we simply work out the molar quantity of silane:

#(15.7*g)/(32.12*g*mol^-1)=0.489*mol#

And #0.489*mol("of silane")xx-1429*kJ*mol^-1("of silane")# #=# #??kJ#.