For the reaction: NH4+(aq) + NO2–(aq) 
N2(g) + 2H2O(l)
Use the experimental data below to determine the rate law and k, the rate constant.
The general form of the rate law (equation) has the rate constant k multiplied by concentrations of reactants.
The exponents on the concentration of reactants are experimentally determined.
For this reaction, the rate law is of the form: rate = k[NH4+]x[NO2-]y.
x and y are determined by how the rate changes if concentrations change:
N2(g) + 2H2O(l)Use the experimental data below to determine the rate law and k, the rate constant.
| Experiment | Initial [NH4+] | Initial [NO2-] | Initial rate |
| 1 | 0.100 | 0.005 | 1.35 x l0-7 s-1 |
| 2 | 0.100 | 0.010 | 2.70 × 10-7 s-1 |
| 3 | 0.200 | 0.010 | 5.40 × 10-7 s-1 |
The general form of the rate law (equation) has the rate constant k multiplied by concentrations of reactants.
The exponents on the concentration of reactants are experimentally determined.
For this reaction, the rate law is of the form: rate = k[NH4+]x[NO2-]y.
x and y are determined by how the rate changes if concentrations change:
As doubling [NH4+] keeping [NO2–] constant doubles the initial rate, x = 1.
As doubling [NO2-] keeping [NH4+] constant doubles the initial rate, y = 1.
Therefore: rate = k[NH4+][NO2– ]
As doubling [NO2-] keeping [NH4+] constant doubles the initial rate, y = 1.
Therefore: rate = k[NH4+][NO2– ]
Calculate k by substituting data for one experiment:
k x 0.100
k = 2.7 × 10-4 s-1 (Note the units depend on x and y.)
k = 2.7 × 10-4 s-1 (Note the units depend on x and y.)