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The following initial rate data are for the reaction of ammonium ion with nitrit

ID: 304357 • Letter: T

Question

The following initial rate data are for the reaction of ammonium ion with nitrite ion in aqueous solution:

NH4+ + NO2- --> N2 + 2 H2O




Complete the rate law for this reaction in the box below.
Use the form k[A]m[B]n , where '1' is understood for m or n and concentrations taken to the zero power do not appear. Don't enter 1 for m or n



From these data, the rate constant is ______M-1s-1.

Experiment [NH4+]o, M [NO2-]o, M Initial Rate, Ms-1 1 0.706 2.74×10-2 6.02×10-6 2 0.706 5.47×10-2 1.20×10-5 3 1.41 2.74×10-2 1.20×10-5 4 1.41 5.47×10-2 2.40×10-5

Explanation / Answer

Sol . As Rate = K [NH4+]m [NO2-]n where k = rate constant , m and n are the order of reaction with respect to NH4+ and NO2- respectively .

So , using the data of experiment no. 1 and put in rate law equation and then , using using the data of experiment no. 2 and put in rate law equation , then , dividing them .

Therefore ,

(6.02 × 10-6)/(1.20 × 10-5) = (0.706/0

706)m × (2.74×10-2 / 5.47 × 10-2 )n

So , 0.5 = (0.5)n , therefore , n = 1.

Now , using the data of experiment no. 2 and put in rate law equation and using the data of experiment no. 4 and put in rate law equation , then , dividing them ,

(1.20 × 10-5)/(2.40 × 10-5) = (0.706/1.41)m × (5.47 × 10-2 /5.47 × 10-2)n

So , 0.5 = (0.5)m , Therefore , m = 1 .

Hence , Rate = k [NH4+] [NO2-]

Now , taking the data of experiment no. 1 , we have ,

6.02 × 10-6 = k × 0.706 × 2.74 × 10-2

So , K = (6.02 × 10-6 ) / ( 0.706 x 2.74 x 10-2 )

K = 3.11 × 10-4 M-1 s-1 .