Please explain in simplest terms! I always get confused! Please help with these
ID: 503527 • Letter: P
Question
Please explain in simplest terms!I always get confused! Please help with these rate laws RVIE.. Department of Chemistry Brooklyn College General Chemistry II: Spring 2017 Lecture Exam 1 Name °C. .19. (8 pts) Consider the gas-phase reaction between nitic oxide and bromine at 273 A(g) 2 Big) The following experimental data were conected M moLI initial rate (Ms) Experiment tial [A] (M 2.4x10 0.10 64.8x10 0.30 Determine the rate law for this reaction (write the statement for the rate law) You have to list experiments numbers for your calculations. rate k. corrtant tripes CAT tn 83. concentretno on rate increa rete k CAT constent. concentration re cense. Overa REP
Explanation / Answer
In order to calculate the rate law expression for a A+B reaction, we need to apply Initial Rates Method.
Note that the generic formula goes as follows:
r = k [A]^a [B]^b
Note that if we got at least 3 sets of point, in which we have A and B constant, then we could use:
r1 / r2 = (k1 [A]1^a [B]1^b) / (k2 [A]2^a [B]2^b)
If we assume K1 and K2 are constant, then K1= K2 cancel each other
r1 / r2 = ([A]1^a [B]1^b) / ( [A]2^a [B]2^b)
Then, order according to [A] and [B]
r1 / r2 = ([A]1/[A2])^a * ([B]1/[B]2)^b
If we get two points in which A1 = A2, then we could get B, and vise versa for A...
From the data shown in YOUR table
Choose point 1 and 2...
r1 / r2 = ([A]1/[A2])^a * ([B]1/[B]2)^b
substitute
(2.4) / (64.8) = (0.1/0.3)^a * (0.20/020)^b
Cleary, the coefficient cancels:
0.03703 = (0.33333)^a
solve,
ln(0.03703) / ln(0.33333) =a
Choose now points 2 and 3:
r1 / r3 = ([A]2/[A]3)^a * ([B]2/[B]3)^b
substitute
(2.4)/(7.2) = (0.10/0.10)^a * (0.20/1.8)^b
Cleary, the coefficient cancels:
0.3333= (0.111)^b
solve,
ln(0.3333) / ln(0.111) = a
a = 0.5
so...
a = 0.5, b = 3
then
r = k [A]^a [B]^b
so
r = k [A]^3 [B]^0.5
order = 3+0.5 = 3.5