Question

Calculate the entropy change (J/mol K) of the given reaction. The molar entropies [J/K-mol] are given in brackets after each substance.

2PbS (s) [91.2] + 3O2 (g) [205.1]$\longrightarrow$2PbO (s) [66.5] + 2SO2 (g) [248.2]

• A. –113.5
• B. –168.3
• C. +72.5
• D. –149.2

Answer 1

Answer: (B)

–168.3

Answer 2

$\Delta$Sreaction = 2 (66.5) + 2 (248.2) – 2 (91.2) – 3 (205.1) = 168.3 J/mole K