0.10ml of a monatomic gas follows the process shown in the figure How much is he
ID: 1512921 • Letter: 0
Question
0.10ml of a monatomic gas follows the process shown in the figure How much is heat energy is transferred to or the gas during process 1 rightarrow 2 ? Express your answer to two significant figure and include the appropriate units How much is heat energy is transferred to or the gas during process 2 rightarrow 3 ? Express your answer to two significant figure and include the appropriate units what is the total change in the thermal energy of the gas Express your answer as an integer and include the appropriate unitsExplanation / Answer
The first law of thermodynamics states that:
U = q + WD
where U is the INCREASE in internal energy of the gas, q is the heat SUPPLIED TO the gas, and WD is the Work done ON the gas.
and 1 atm = 101000Pa
(a)process 1->2
constant pressure expansion: WD by gas = 4(101000)x(0.8x10^-3) = 323.2J
U = 3/2P(V) = 3/2(4x101000)(0.8x10^-3) = 484.8J
q = U - WD
= 484.8 - (-323.2)
= 808J (heat supplied TO the gas, since answer is positive)
(b)process 2->3
constant volume, reduction in pressure => no WD on/by gas
hence from the eqn above
q = U
= 3/2V(P)
= 3/2(1.6x10^-3)(2-4)(101000)
= -484.8J (heat released FROM gas, since answer is negative)
(c)total change in thermal energy
= final U - initial U
= 3/2(202000)(1.6x10^-3) - 3/2(404000)(0.8x10^-3)
= 484.8 - 484.8
= 0J
EXTRA: if you notice, since the thermal energy change is 0J from 1->3, it means that the temperature of the gas has returned back to the original temperature
EXTRA EXTRA:
you can also use the first law to calculate the total U as such:
U = q(total) + WD(total)
= (808-484.8) + (-323.2)
= 0J
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