Of the following reactions, which involves the largestdecrease in entropy? 1.CaCO3(s) to CaO(s)+CO2(g) 2.CO(s)+O2(g) to 2 CO2(g) 3. Pb(NO3)2(s)+ 2 KI(s) to PbI2(s) + 2KNO3(s) 4. C3H8(g) + 5O2(g) to 3 CO2(g) + 4 H2O(g) 5. 4La(s) + 3 O2(g) to 3 La2O3(s) Of the following reactions, which involves the largestdecrease in entropy? 1.CaCO3(s) to CaO(s)+CO2(g) 2.CO(s)+O2(g) to 2 CO2(g) 3. Pb(NO3)2(s)+ 2 KI(s) to PbI2(s) + 2KNO3(s) 4. C3H8(g) + 5O2(g) to 3 CO2(g) + 4 H2O(g) 5. 4La(s) + 3 O2(g) to 3 La2O3(s)
Explanation / Answer
1. Gains entropy because increase in disorder (gasstate) 2. Gains entropy because increase in disorder (1 mol gas to 2mol gas) 3. About equal entropy because there is no phase change 4. Gain entropy because increase in disorder (6 mol gas to 7mol gas) 5. Lose entropy because decrease in disorder (solid is moreordered than gas)