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2.-When water boils at 2 atm, the heat of vaporization is 2.2 106 J/kg, and the boiling point is 120ºC. At that pressure, 1 kg of steam occupies a volume of 0.824 m3, while 1 kg of water occupies 10-3 m3.
a) Find the work done when 1 kg of steam is formed at that temperature.
b) Calculate the increase in internal energy.

Respuesta :

a) Find the work done when 1 kg of steam is formed at that temperature.

  • p = pressure = 2 atm =2 101325.2738 = 202651 Pa
  • V₁ = volume of 1kg of water = 10⁻³ m³
  • V₂ = volume of 1 kg of steam = 0.824 m³
  • Lf = heat of vaporization of water = 2.2 10⁶ J/kg
  • m = mass of water = 1 kg

[tex]\bf{W=p(V_{2}-V_{1})=166781 \ J }[/tex]

[tex]\boxed{\bf{W=166781 \ J}}[/tex]

b) Calculate the increase in internal energy.

[tex]\Delta U=Q-W\\Q=mL_{f}=2,2\cdot10^{6} \ J\\\Delta U=2,033\cdot10^{6} \ J\\\boxed{\Delta U=2,033\cdot10^{6} \ J}[/tex]

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