Question

What is the change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies.

Answer 1

Answer: The change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies is 20 cal/K.

Step-by-step explanation:

`Pb(l)\rightleftharpoons Pb(s)`

`\Delta S=(q)/(T)`

`{\text{Change in entropy}}=(heat)/(Temperature)`

T is the temperature at which the process is carried out, here the temperature is constant, 327.5°C =
`(273+327.5)K=600.5K` ,because only phase change occurs.

q = heat given in the process =
`m* L_f`

m = mass of lead = 2.0 kg

`L_f` = latent heat of fusion of lead = 5.9 kcal/kg

`\Delta S=(2kg* 5.9kcal/kg)/(600.5K)`

`\Delta S=0.02 kcal/K=20cal/K`

Thus the change in entropy of the lead when 2.0 kg of molten lead at its melting point temperature solidifies is 20 cal/K.