Question

 Entropy, denoted by the symbol S, is the thermodynamic property describing the amount of molecular randomness or disorder in a system. It is a state thermodynamic function, meaning that its value does not depend on the path used to arrive at a specific set of conditions. Each system with a specified temperature, pressure, and composition has a unique entropy value.

 The entropy change, ΔS, is the difference in entropy between two states of a system, such as between the reactants and products of a reaction or between a flask before and after adding a mixture of gas.

 Part B

 Calculate the standard-state entropy for the following reaction:

 1 Al2O3(s) + 3 H2(g) → 2 Al(s) + 3 H2O(l)

 (If applicable, coefficients of one have been included for clarity.) The standard entropy values are given in the table.

Answer 1

Srxn = Sproducts - Sreactants

Srxn = 2*28 + 3*189 - (51 + 3*131) = 179 J/moK

Srxn = 179 J/moK