Question

# Consider the reaction of ammonium ions (NH4+) and nitrite ions (NO2-) shown in equation below:      ...

Consider the reaction of ammonium ions (NH4+) and nitrite ions (NO2-) shown in equation below:

NH4+ (aq) + NO2-(aq) → N2(g) + 2 H2O(l)

 Determination Number Initial [NH4+], M Initial [NO2-], M Initial rate, Ms-1 1 0.15 0.0075 3.0 x 10-7 2 0.15 0.015 6.0 x 10-7 3 0.30 0.015 1.2 x 10-6

(a) Use method of initial rates to find the order of the reaction with respect to NH4+.

(b) Use the method of initial rates to find the order of the reaction with respect to NO2-.

(c) Calculate the rate constant, k for the reaction of NH4+ and NO2-.

Divide the rate 2 / rate 1 = 0.15 x 0.15 / 0.15 x 0.0075 = 6 x 10-7 / 3 x 10-7

2[NO2-] = 21

According to [NO2-] the order of the reaction is one

Divide the rate 3 / rate 2 = 0.3 x 0.015 / 0.15 x 0.015 = 1.2 x 10-6 / 6 x 10-7

2[NH4+] = 21

According to [NH4+] the order of the reaction is one

hence we can write the rate law

R = k [NO2-] [NH4+]

To calculate rate constant substitute the values in the equation

Rate constant k = 0.15 x 0.0075 / 3.0 x 10-7

Rate constant k = 3.75 x 103 M/S

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