A. If a thermodynamic system is taken along a path A along which -25.4 J flows i

Question

A. If a thermodynamic system is taken along a path A along which  -25.4 J flows into the system and 76.4 J of work is done on the system, what is the change in internal energy, ?U?
?U: 1      J
B. If the same system is taken along a second path B for which the endpoints are the same so that ?U is the same, but 76.2 J of heat Q flows into the system, what is the work W done along that path? (?U only depends on the endpoints of the path, not the whole path. Q and W depend upon the whole path.)
W: 2      J

C. If further this same system is taken along a third path C for which the endpoints are the same so that ?U is the same, but -35.5 J of work W is done on the system, how much heat, Q, flows into the system?
Q: 3      J

Explanation / Answer

(A)

basic assumption is that

q flowing into the the system is (+ve) work done

w done by the system is +ve

so w= (-76.4)

so 1 st law is q=w+u

dU=dq-dw = (-25.4) - (-76.4) = 51 Joules

(B)

Convention remaining the same

dU= 51

dq =76.2

dw = dq-dU = 76.2-51 =25.2 Joules

(C)

Convention remaining the same

du = 51

dw =-(35.5)

dq= dw+du = 15.5 Joules

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.