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A gas expands when 606 j of energy is added to it as heat. the expanding gas does 418 j of work on its surroundings.
a. what is the overall change in the internal energy of the gas?
b. if the work done by the gas were equal to 1212 j (rather than 418 j)

Respuesta :

carlosego
a)
 Q=606 J 
 W = 418 J 
 From first law of thermodynamics, 
 [ Uf - Ui ] = Q - W 
 [ Uf - Ui ]=606 -418=188 J 
 [ Uf - Ui ]= 188 J 
 
b )
 W2 = 1212 J 
 Q2 = ? 
 Ui2=Uf =Ui +188
 Uf2=Ui
 [ Uf2 - Ui2 ]=Ui-(Ui+188)
 -188 J 
 Q2=W2+(Uf2 -Uf1) 
 Q2 =1212 -188=1024 J 
 Q added in second step (b) so that internal energy is equal to initial internal energy of step (a)=1024 J

W0lf93
a) Heat added Q=606 J  
Work W = 418 J   
From first law of thermodynamics,  
 Change in internal energy [ Uf - Ui ] = Q - W  
 Change in internal energy [ Uf - Ui ]=606 -418=188 J 
 
 Change in internal energy [ Uf - Ui ]= 188 J  
 b ) work W2 = 1212 J  
 heat exchanged Q2 = ?  
 Initial energy of this process Ui2=Uf of previous=Ui +188 

 
 Final energy Uf2=initial energy of previous process=Ui  
 Change in internal energy of second process= [ Uf2 - Ui2 ] 
 
 Change in internal energy of second process=Ui-(Ui+188)  
 Change in internal energy of second process= -188 J  
 Q2=W2+(Uf2 -Uf1)  

 Q2 =1212 -188=1024 J

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