Question

Suppose two blocks of iron, each having 1 mol of iron atoms, are at differing temperatures and are then brought together in an otherwise isolated system. One of the blocks is at 273.15 K and the other is at 373.15 K and the process is carried out at 1 bar pressure.

a.) Would you expect ∆Ssys < 0, ∆Ssys = 0, ∆Ssys > 0 ?

b.) Using common sense and high school physics (and perhaps the First Law), what is the common final temperature of the two blocks?

c.) Calculate ∆Ssys for the process (use Table 4.1 for any needed molar heat capacities needed, and assume that the molar heat capacities are independent of T).

d.) What is q for the isolated system? How does this value of q and the result of part C relate to the Clausius inequality: final initial d q S T − ∆ ≥ ∫ ?

e.) Interpret this change in entropy in terms of the ordering-disordering effects involved in the transfer of given amount of heat from a block at higher temperature to one at a lower temperature (i.e. the disordering effect of adding a given q to the cooler block vs the ordering effect of removing the same q from the hotter block).

Molar heat capacity of Fe(s) ==> Cp,m (J / mol*K) = 25.1

Answer 1