Question

# Consider the gas-phase reaction between nitric oxide and bromine at 273 ∘C 2NO(g)+Br2(g)→2NOBr(g). The following data...

Consider the gas-phase reaction between nitric oxide and bromine at 273 ∘C
2NO(g)+Br2(g)→2NOBr(g).
The following data for the initial rate of appearance of NOBr were obtained:
 Experiment [NO](M) [Br2](M) Initial Rate of Appearance ofNOBr(M/s) 1 0.10 0.20 24 2 0.25 0.20 150 3 0.10 0.50 60 4 0.35 0.50 735

Part D

What is the rate of disappearance of Br2 when [NO]= 7.6×10−2 M and [Br2]=0.21 M ?

Let the rate (-r) = K[ NO]m [Br2]n

m and n are orders with respect to [NO] and [Br2] respectively

from experiment 1

24= K[0.1]m [0.2]n      (1)

From experiments 2

150= K[0.25]m [0.2]n      (2)

Eq.2/ Eq.1 gives   (2.5)m= 6.25 , m=2

From experiment 3

60= K[0.1]m [0.5]n      (3)

Eq.3/ Eq.1 gives 60/24= (0.5/0.20)n, 2.5= 2.5n,   n=1

The rate becomes –r= K[[NO]2 [Br]1

From Eq.1 24= K[ 0.1]2 [0.2]1

K=12000 /M2.sec

So the rate becomes –r = 12000[ NO]2 [Br]1

The validity of this equation for experiments 4 is also verified.

when [NO] =7.6*10-2 M and [Br2]=0.21M

Rate -r =12000*[7.6/100)2 [0.21]=14.55 M/s

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