ch20-p015

# ch20-p015 - 15 The ice warms to 0C then melts and the...

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Melting is an isothermal process. The energy leaving the ice as heat is mL F , where L F is the heat of fusion for ice. Thus, Δ S = Q / T = mL F / T = (0.010 kg)(333 × 10 3 J/kg)/(273 K) = 12.20 J/K. For the warming of the water from the melted ice, the change in entropy is =l n , f w i T Sm c T Δ where c w is the specific heat of water (4190 J/kg K). Thus, () ( ) 288 K = 0.010 kg 4190 J/kg K ln = 2.24 J/K. 273 K S §· Δ⋅ ¨¸ ©¹ The total change in entropy for the ice and the water it becomes is = 0.828 J/K +12.20 J/K + 2.24 J/K =15.27 J/K. S Δ Since the temperature of the lake does not change significantly when the ice melts, the change in its entropy is Δ S = Q / T , where Q is the energy it receives as heat (the negative of the energy it supplies the ice) and T is its temperature. When the ice warms to 0 ° C, ( ) ( ) = = 0.010 kg 2220 J/kg K 10 K = 222 J. If i Qm c T T −− When the ice melts, L F = = 0.010 333 10 = 3.33 10 . 33 × × kg J / kg J af ch When the water from the ice warms, c T T wf i = = 0.010 4190 15 = 629 .

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## This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

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ch20-p015 - 15 The ice warms to 0C then melts and the...

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