1.

Calculate the entropy change in system if 2 mole of methane undergoes complete combustion at 300 K from the following data. Given data `:DeltaH_("cumbustion")^(@) CH_(4)(g)=-900kJ,DeltaG_(f)^(@)CH_(4)(g)=-40,DeltaG_(f)^(@)(H_(2)O)(l)=-120, DeltaG_(f)^(@)CO_(2)(g)=-400kJ//mol` Instruction:- If your answer is -ve, then wire double the magnitude as your final answer For example : If `DeltaS_("surr")=+20J/K` then write your answer as 20 but if `DeltaS_("surr")=-20` then write your answer as 40 Express your answer in J/K.

Answer» [4000]
`2CH_(4) to 4O_(2) to 2CO_(2)++4H_(2)O`
`DeltaH^(@)=-900xx2=-1800kJ`
`DeltaG^(@)=DeltaG_("f Products")^(@)-DeltaG_("f Reactant")^(@)`
`=(-400)xx2+4(-120)-[2xx(-40)+0]`
=-800-480+80
=-1200kJ/mol
`DeltaG^(@)=DeltH^(@)-TDeltaS^(@)`
`DeltaS_("system")^(@)=(DeltaH^(@)-DeltaG^(@))/(T)`
`((-1800)-(-1200)kJ)/(300)=(-600)/(300)kJ`
`-2kJ=-2000J//K`
Final answer4000


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