Chapter 11 Rate of Reaction 11 11.1
? Rate Law Kinetics : 11 11.2
CO(g) + NO 2 (g) CO 2 (g) + NO(g) E a =134 kj CO(g) + NO 2 (g) H = -226 kj CO 2 (g) + NO(g) 11 11.3
N 2 O 5 (g) 2NO 2 (g) + 1/2 O 2 (g) Concentration(mol/L) [NO 2 ] [O 2 ] [N 2 O 5 ] Time(min.) 11 11.4
11.1 (reaction rate) Instantaneous rate =dc/dt C (=C 2 -C 1 ) average rate = C/ t t(=t 2 -t 1 ) t 1 t 2 11 11.5
N 2 O 5 (g) 2NO 2 (g) + 1/2 O 2 (g) [NO 2 ] [NO 2 ] rate = - [N 2 O 5 ] / t = [NO 2 ]/2 t [N 2 O 5 ] [N 2 O 5 ] t 1 t 2 t 11 11.6
aa+ bb cc+ dd rate = [C] = [D] = - [A] = c t d t a t - [B] b t ( ).,,, : mol/l S 11 11.7
11 11.8
11.2 Mg(s) + 2H + (aq) Mg 2+ (aq) + H 2 (g) 6.0M HCl 0.3 M HCl 0.3M 6.0M HCl HCl 11 11.9
:A rate = k[a] m k=, m = (order) : A, B rate = k[a] m [B] n (overall order) = m+n, m n (1, 2, 3, 0, ½..) ( ) 11 11.10
- m k : CH 3 CHO(g) CH 4 (g) + CO(g) rate 2.0 M/s 0.50 M/s 0.080 M/s [CH 3 CHO] 1.0 M 0.50 M 0.20 M rate = k[a] m rate 1 /rate 2 ={[A 1 ]/[A 2 ]} m 2.0 / 0.50 = (1.0 / 0.50) m m = 2, rate = k[ch 3 CHO] 2 k = rate/[ch 3 CHO] 2 = 2.0 M/s = 2.0(M s) -1 (1.0 M) 2 11 11.11
11.3 1 (First order reactions) A products rate=-d[a]/dt = k[a] : -d[a]/[a] = k dt : - (d[a] /[A]) = kdt : -ln[a] = kt [A] 0 ln = kt; [A] [A] [A] 0 t 0 [A] 0 = A, [A] = t A 11 11.12
1 k = 0.250 /s, [A] 0 = 1.00 M, 10.0 s A? ln [A] 0 / [A]= 0.250 10.0 = 2.50 [A] 0 / [A] = e 2.50 =12.2 [A] = 1.00 M/12.2 = 0.0819 M ( )? [A] = [A] 0 /2; [A] 0 /[A] = 2 ln 2 = kt ; t 1/2 = ln 2/k = 0.693/0.250 = 2.77 s 1 :, k t 1/2 11 11.13
0 2 0 : rate = k ; [A]=[A] 0 - kt; plot of [A] vs. t is linear 2 : rate = k[a] 2 ; l/[a] - l/[a] 0 = kt plot of l/[a] vs. t is linear 11 11.14
Late Law 11 11.15
0? 1? 2? 11 11.16
11.4 11 11.17
: ) CO(g) + NO 2 (g) CO 2 (g) + NO(g) 11 11.18
NO(g) + O 3 (g) NO 2 (g)+ O 2 (g) 1. or 2. 3. 11 11.19
(Collision model) k = p Z f, f= e -E a /RT., p, Z, f,. A (E a ) R= Reactants E R P A= Activated Complex P= Products 11 11.20
(Activated complex) : ) CO(g) + NO 2 (g) CO 2 (g) + NO(g) 11 11.21
(1, 2 ) CH 3 Cl + F - F---CH 3 ---Cl CH 3 F + Cl - 11 11.22
11.5. T k 10 º C 2. : 11 11.23
Arrhenius : ln k = ln A-E a /RT; R = 8.31 J/K, E a in joules ln k vs. 1/T -E a /R 11 11.24
T 1, T 2 ln k 1 = ln A-E a /RT 1 ln k 2 = ln A-E a /RT 2 ln k 2 - ln k 1 = -(E a /RT 2 -E a /RT 2 ) : ln k 2 /k 1 = E a [1/T 1-1/T 2 ]/R 11 11.25
25 35 C 2, E a? ln k 2 /k 1 = 0.693 = E a [1/298-1/308]/8.31 E a = 5.3 10 4 J = 53 kj 11 11.26
11.6 (Catalysis). 11 11.27
2H 2 O 2 (aq) 2H 2 O + O 2 (g) H 2 O 2 : E a. I - : H 2 O 2 (aq) + I - (aq) H 2 O + IO - (aq) H 2 O 2 (aq) + IO - (aq) H 2 O + O 2 (g) + I - (aq) 2H 2 O 2 (aq) 2H 2 O + O 2 (g) E a 11 11.28
Catalytic converter 11 11.29
11.7 : 11 11.30
. :?; =. 11 11.31
X 2 A 2 3. First, X 2 : X 2 (g) 2X(g) ; fast rate constants = k 1 (forward), k -1 (reverse) X(g) + A 2 (g) AX(g) + A(g) ; slow rate constant = k 2 A(g) + X 2 (g) AX(g) + X(g) rate of reaction = rate slow step = k 2 [X] [A 2 ] 11 11.32
X, note that: k 1 [X 2 ] = k -1 [X] 2 [X], : rate = k 2 (k 1 ) 1/ 2 (k 1 ) 1/2 [X 2] 1/ 2 [A 2 ] A 2 1, X 2 1/2 11 11.33