A spring-loaded piston-cylinder contains 1 kg of carbon dioxide. This system is heated from 104 kPa and 25 °C to 1,068 kPa and 311 °C. Determine the total heat transfer to this system in kJ. Give your answer with three decimal points

Respuesta :

Answer:

Q = -68.859 kJ

Explanation:

given details

mass [tex]co_2 = 1 kg[/tex]

initial pressure P_1 = 104 kPa

Temperature T_1 = 25 Degree C = 25+ 273 K = 298 K

final pressure P_2 = 1068 kPa

Temperature T_2 = 311 Degree C = 311+ 273 K = 584 K

we know that

molecular mass of [tex]co_2 = 44[/tex]

R = 8.314/44 = 0.189 kJ/kg K

c_v = 0.657 kJ/kgK

from ideal gas equation

PV =mRT

[tex]V_1 = \frac{m RT_1}{P_1}[/tex]

       [tex]=\frac{1*0.189*298}{104}[/tex]

[tex]V_1 = 0.5415 m3[/tex]

[tex]V_2 = \frac{m RT_2}{P_2}[/tex]

     [tex] =\frac{1*0.189*584}{1068}[/tex]

[tex]V_1 = 0.1033 m3[/tex]

WORK DONE

[tex]W =P_{avg}*{V_2-V_1}[/tex]

w = 586*(0.1033 -0.514)

W =256.76 kJ

INTERNAL ENERGY IS

[tex]\Delta U  = m *c_v*{V_2-V_1}[/tex]

[tex]\Delta U  = 1*0.657*(584-298)[/tex]

[tex]\Delta U  =187.902 kJ[/tex]

HEAT TRANSFER

[tex]Q = \Delta U  +W[/tex]

   = 187.902 +(-256.46)

Q = -68.859 kJ