Thermodynamics Question 215
Question: When an ideal gas in a cylinder was compressed isothermally by a piston, the work done on the gas was found to be $ 1.5\times 10^{4}\ joules $ . During this process about
[MP PMT 1987]
Options:
A) $ 3.6\times 10^{3} $ cal of heat flowed out from the gas
B) $ 3.6\times 10^{3} $ cal of heat flowed into the gas
C) $ 1.5\times 10^{4} $ cal of heat flowed into the gas
D) $ 1.5\times 10^{4} $ cal of heat flowed out from the gas
Show Answer
Answer:
Correct Answer: A
Solution:
In isothermal compression, there is always an increase of heat.
Which must flow out the gas.
$ \Delta Q=\Delta U+\Delta W\Rightarrow \Delta Q=\Delta W\ \ (\because \ \Delta U=0) $
Therefore $ \Delta Q=-1.5\times 10^{4}J=\frac{1.5\times 10^{4}}{4.18}cal=-3.6\times 10^{3}cal $
