Question

(a) For an isolated system ΔU = 0; what will be ΔS? (b) For a reaction at 298 K 2A + B————->C ΔH = 400 kj mol-1 and ΔS = 0.2 kj K-1 mol-1. At what temperature will the reaction become spontaneous considering ΔH and ΔS to be constant over the temperature range?

Predict in which of the following the entropy increases or decreases: (a) A liquid crystallizes into a solid (b) Temperature of a crystalline solid is raised from 0K to 115K (c) 2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g) (d) H2(g) → 2H(g)

(a) Define entropy. (b) Why is entropy a state function?