1) A gas is heated and is allowed to expand such that it follows a horizontal li

Question

1)     A gas is heated and is allowed to expand such that it follows a horizontal line path on a PV diagram from its initial state (1.0 x 10^5 pa, 1.0 m^3) to its final state (1.0 x 10^5 pa, 2.0m^3) calculate the work done by  the gas on its surroundings  

2)     A gas is heated such that it follows a vertical line path on a PV diagram from its initial state (1.0 x 10^5 Pa, 1.0 m^3) to its final state (2.0 x 10^5 Pa, 3.0 m^3). Calculate the work done by the gas on its surroundings.

3)     A sealed cylinder has a piston and contains 8000 cm^3 of an ideal gas at a pressure of 8.0 atm. Heat is slowly introduced and the gas isothermally expands to 16000 cm^3. How much work does the gas on the piston?

4)     An ideal gas expands isothermally, performing 8.8kJ of work in the process. Calculate the heat absorbed during the expansion

5)     A gas contained in a cylinder that has a piston is kept at a constant pressure of 2.8 x 10^5 Pa. the gas expends from 0.5 m^3 to 1.5 m^3 when 300 kJ of heat is added to the cylinder. What is the change in internal energy of the gas?

Explanation / Answer

1) W = P*(V2-V1) = 1*10^5*(2-1) = 10^5 J

2) W = P*(V2-V1) = 0

3)

no of moles is not given.

i assume n = 1


v1 = 8000 cm^3 = 8*10^-3 m^3

P1 = 8 atm = 8*1.013*10^5 = 8.104*10^5 pa

T1 = P1*V1/(n*R) = 779.8 K

W = n*R*T*ln(V2/V1)

= 1*8.314*779.8*ln(16000/8000)

= 4493.85 J

4) dQ = dU + dW

in isothermal process dU = 0

dQ = dW = 8.8 kJ

5)

dW = P*(V2-V1) = 1*10^5*(1.5-1) = 10^5 J

dQ = 3*10^5 J

dQ = dU + dW

dU = dQ - dW


   = 2*10^5 J

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