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as T , k. As temperature increases, rate increases because. (WHY does T affect rate = k [A] [B]?). collision model : explains how rate is affected by [ ] and by temperature. -- greater [ ]:. more collisions per sec. -- higher temperature:. faster particles, more
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as T , k . As temperature increases, rate increases because... (WHY does T affect rate = k [A] [B]?) collision model: explains how rate is affected by [ ] and by temperature -- greater [ ]: more collisions per sec. -- higher temperature: faster particles, more collisions per sec., activation energy (Ea) is exceeded more often
activated complex: the temporary arrangement of atoms btwn. “R” arrangement and “P” arrangement About DE... + Ea -- it is ___ for endo. and___ for exo. Ea of reverse reaction – R Energy -- it has NO effect on the reaction rate DE P Time
e.g., Cl + NOCl Cl2 + NO ( ) k1 Ea 1 1 ln = – k2 R T2 T1 For the reaction to occur, collisions must take place with particles oriented in a certain way. Cl Cl NOCl NOCl “NOPE.” “YEP.” For a given reaction, the Ea relates rate constants at two different temps WITH those temps. Ea in J/mol R = 8.314 J/mol-K T = absolute temp.
T (oC) k (s–1) 189.7 2.52 x 10–5 251.2 3.16 x 10–3 ( ) k1 Ea 1 1 ln = – k2 R T2 T1 Using the following information, find... (1) ...Ea (2) ...k at 430.0 K (1) Ea = 1.59 x 105 J/mol = 159 kJ/mol
T (oC) k (s–1) 189.7 2.52 x 10–5 251.2 3.16 x 10–3 Using the following information, find... (1) ...Ea (2) ...k at 430.0 K (2) (take “e-to-the-both-sides”…) (Using T = 524.4 K and k = 3.16 x 10–3 gives k430 = 1.05 x 10–6 s–1) k430 = 1.07 x 10–6 s–1