Entropy Entropy is often described as randomness,or freedom to move,or disorder. Reactions tend to favor products with greatest entropy Note the sign of the entropy contribution to AG: A +ve AS term makes a favorable contribution to the free energy. For the chlorination of methane,AS=2.9 entropy units(eu) So -T△S°=-298Kx2.9=-0.86kcal/mol Remember△H°=-25kcal,(much larger) So△G°=-25-0.86=-26kcal/mol (Often AG is approximated to be equal to AH). In kJ... △G°=△H°-T△S°=-105.1kJ/mol-3.61kJ/mol =-108.7 kJ/mol (-25.9 kcal/mol) Ch04 Rates +Kinetics (landscape) Page 10 Ch04 Rates + Kinetics (landscape) Page 10 Entropy Entropy is often described as randomness, or freedom to move, or disorder. Reactions tend to favor products with greatest entropy. Note the sign of the entropy contribution to G: A +ve S term makes a favorable contribution to the free energy. For the chlorination of methane, S° = 2.9 entropy units (eu) So -TS° = -298K x 2.9 = -0.86kcal/mol Remember H° = -25kcal, (much larger) So G° = -25 - 0.86 =-26kcal/mol. (Often G is approximated to be equal to H). In kJ…