For a chemical reaction the values of DeltaH and DeltaS at 300 K are - 10 kJ "mol"^(-1) and -20 J "deg"^(-1) "mol"^(-1) respectively. What is the value of DeltaG of the reaction? Calculate the DeltaG of a reaction at 600K assuming DeltaH and DeltaS values are constant. Predict the nature of the reaction.

For a chemical reaction the values of DeltaH and DeltaS at 300 K are -

1.	For a chemical reaction the values of DeltaH and DeltaS at 300 K are - 10 kJ "mol"^(-1) and -20 J "deg"^(-1) "mol"^(-1) respectively. What is the value of DeltaG of the reaction? Calculate the DeltaG of a reaction at 600K assuming DeltaH and DeltaS values are constant. Predict the nature of the reaction.
Answer» Solution :`DeltaH=-10 "kJ mol"^(-1) =-10000 "J mol"^(-1)` `DeltaS=-20 J K^(-1) "mol"^(-1)` T=300 K `DELTAG`=? `DeltaG=DeltaH-TDeltaS` `DeltaG=-10 "kJ mol"^(-1) -300 K xx (-20 xx10^(-3))kJ K^(-1) "mol"^(-1)` `DeltaG=(-10+6) "kJ mol"^(-1)` `DeltaG=-4 "kJ mol"^(-1)` At 600 K `DeltaG=-10 "kJ mol"^(-1) -600 K xx(-20 xx10^(-3))kJ K^(-1) "mol"^(-1)` `DeltaG=(-10+12) "kJ mol"^(-1)` `DeltaG=+2 kJ mol^(-1)` The VALUE of `DeltaG` is NEGATIVE at 300K and the reaction is spontaneous, but at 600K the value `DeltaG` BECOMES positive and the reaction is non-spontaneous.