Entropy chance with a carnot cycle?

[coffeem]

in a carnot cycle the gas expands adiabatically from 200 degrees to 500 degrees. what is the efficecy? and what is the entropy change of the gas during the expansion?

sorry - i got the efficiency to be: 38.8%

however I am unsure how to work out the entropy chance? any hints?

 

[coffeem]

however my thinking is that if the the system is adiabatic... then the entropy will stay constant... then it will be 0? am i on the right lines? thanks

 

[coffeem]

Hi I am still struggling with this. any advice? thanks

 

[rock.freak667]

however my thinking is that if the the system is adiabatic... then the entropy will stay constant... then it will be 0? am i on the right lines? thanks

If ΔS=dQ/T and dQ=0 for an adiabatic process then ΔS=0. So you are right.