[填空题]
Consider the followirxr4(b e o mw3uz:43ok+hgi;xnjkky i4tsj ,gw*3k fqmc2 i1;pa2qw/x21vd*t g reaction:
$C_2H_4$(g)+$H_2$(g)→$C_2H_6$(g)
ΔH −136kJ mol$^{-1}$
ΔS −121JK$^{-1}$mol$^{-1}$
ΔG at 298K −99.9kJ mol$^{-1}$
1.1Explain why the enthalpy of formation of $H_2$ is 0kJmol$^{-1}$.
1.2Explain why the entropy change for this reaction is negative.
2.Explain how a reaction can be spontaneous with a negative entropy change.
3.Calculate the temperature at which this reaction is no longer spontaneous.
T= K
