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20) A cylinder contains 2 moles of helium gas at a temperature of 300 K. If the

ID: 1298996 • Letter: 2

Question

20) A cylinder contains 2 moles of helium gas at a temperature of 300 K. If the gas is heated at a constant Volume, how much energy. Q. must be transferred by heat to the gas for its temperature to increase to BOO K? Choose from the best answer below a) Q 7482.6 J; Q 2492 2 J; C) Q 4988 4 J; or d) Q = 11223.9J 21) The Kelvin temperature scale identifies what is known as absolute zero, i.e., T = 0 K. Is it possible to cool to exactly T = 0 K? a) Yes, it is possible to cool to T = 0 K; or b) No. it is not possible to cool to T = 0 K

Explanation / Answer


20)

dQ=dU+dW

but at constant volume dW=0

heat suplied to system=increase in internal energy

dU=dQ=n*Cv*dT

=2*(3R/2)*(600-300) (helium is monoatomic gas Cv=3R/2)

=2*(3*8.314/2)*300

=7482.6 J

option (a) is correct


21)

option (b) is correct

it is not possble to cool to T=0 k

this condition is not possible practically