Suppose we have a pot of water that we are boiling and pretend we can tell the d

Question

Suppose we have a pot of water that we are boiling and pretend we can tell the difference between the steam and surrounding air. The total mass of the water in the pot is 1 kg. The water is initially at 80 degree Celsius and it is turned into steam at 120 degree Celsius and it is held at a constant pressure of 101,000 Pa. The density of water at 80 degree Celsius is 958.4 kg/m3 . The steam is confined to a space of 0.004 m3 .

a.) Find the heat added to the water.

b.) Find the work done by the steam on the enviornment.

c.) Find the change in internal energy of the system.

Explanation / Answer

apply the quantity of heat Supplied Q = mcDT

where m is mass

c is Sp heat = 4.186

Dt is the change of temp

Q = 1 * 4.186 * (120-80)

Q = 167.44 Joules

--------------------------------

b. apply Work Done W = PdV

P is pressure and dV is the Volume

so W = 101000* 0.004

W = 404 Joules

------------------------

apply dQ = dU + dW

so

internal eenrgy dU = dQ- dW

dU = 167.44-404

dU = -236.56 Joules

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