1. Calculate the average H-S bond enthalpy in H2S(g) given the standard enthalpies of formation for H2S(g), H(g), S(g) as -20.1 kJ, 218kJ and 223kJ/mol respectively.
a. 461 kJ/mol
b. 679 kJ/mol
c. 340 kJ/mol
d. 10.1 kJ/mol
e. 231 kJ/mol
Alright, so i wrote the equation as
H2S --> 2H + S
and i found the enthalpy for the reaction as 679 kJ/mol...my questions is how do you get the average H-S bond? would you have to divide 679/2 since there is 2 moles of H and therefore get 340 kJ/mol?
2. The change in internal energy for combustion of 1 mole of CH4(g) in a cyclinder according to the reaction
CH4(g) + 2O2(g) --> CO2(g) + 2H20(g)
is -836.3 kJ. If a piston connected to the cylinder performs 567 kJ of expansion work due to the combustion, how much heat is lost from the system( the reaction mixture)?
Would you use the equation
delta E= q + w
-836.3= q + (-567) q= -269 kJ
does that seem right? also since they ask for how much heat is lost can i just answer q= 269 kJ instead of -269 kJ? thanks