(a) Consider the following two stage process: Stage 1. The system absorbs 83 J o
ID: 1049735 • Letter: #
Question
(a) Consider the following two stage process:
Stage 1. The system absorbs 83 J of heat and during this process it had 44 J of work done on it.
Stage 2. The system absorbs 63 J of heat and during this process it does 27 J of work on the surroundings.
Calculate Q, w, and E for the overall process
(b) A piston is compressed from a volume of 7.5 L to 2.2 L at a constant pressure of 1.5 atm. During this process, the system also absorbs 266 J of heat. Calculate E for this process.
Explanation / Answer
a). Total energy absorbs = 83+63 =146j
Q = 146J
w=44-27 = 17J , w is +ve sign because workdone on the system
E= Q+w = 146 + 17 = 163 J.
b).Volume change = V = 7.5-2.2 = 5.3 L
P = 1.5 atm
W= PV = 1.5 x 5.3 = 7.95 L-atm = 7.95 x 101.325J = 805.534 J ( 1 L-atm = 101.325J)
Q = 266 J
E = Q +W = 266 - 805.534 = - 539.534 J ( W is +ve because workdone onthe system)
E= - 539.5 J.
.
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