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E. A + B. C Products. Reaction Coordinate . Products C. Endothermic Δ E > 0 E act > 0. E. A + B. Reaction Coordinate . Products C. E. Endothermic Δ E > 0 E act = 0. A + B. Reaction Coordinate . Products C. E. A + B. Exothermic Δ E < 0 E act > 0.
E N D
E A + B C Products Reaction Coordinate Products C
Endothermic ΔE > 0 Eact > 0 E A + B Reaction Coordinate Products C
E Endothermic ΔE > 0 Eact = 0 A + B Reaction Coordinate Products C
E A + B Exothermic ΔE < 0 Eact > 0 Reaction Coordinate Products C
E A + B Exothermic ΔE < 0 Eact = 0 Reaction Coordinate Products C
A + B C (products) Many ion-molecule reactions such as
A + B C (products) Many ion-molecule reactions such as H3+ + CO HCO+ + H2
A + B C (products) Many ion-molecule reactions such as H3+ + CO HCO+ + H2 …in which a proton H+ has been transferred to the CO molecule are endothermic with zero activation energy and occur on every 2-body collision
Endothermic Eact > 0 E Endothermic Eact = 0 A + B Exothermic Eact > 0 Exothermic Eact = 0 Reaction Coordinate Products C Harry Kroto 2004
A + B C (products) (d/dt) nc = knanb k = e-Eact/kT = v = 4 x 10-11 cm3 s-1 at 100K For an ion molecule reaction k = (4)-½ 2(e2/)½ = 2x10-9 cm3 Rate for most ion molecule reactions Reaction on every 2-body collision Harry Kroto 2004