Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

NH4+ (aq) + NO2- (aq) ? N2 (g) + H2O (l) Experiment [NH4+]i [NO2-]i Initial rate

ID: 766579 • Letter: N

Question

NH4+ (aq) + NO2- (aq) ? N2 (g) + H2O (l) Experiment [NH4+]i [NO2-]i Initial rate (M/s) 1 0.24 0.10 7.2 x 10-4 2 0.12 0.10 3.6 x 10-4 3 0.12 0.15 5.4 x 10-4 4 0.12 0.12 4.3 x 10-4 First determine the rate law and rate constant. Under the same initial conditions as in Experiment 4, calculate [NH4+] at 256 seconds after the start of the reaction. In this experiment, both reactants are present at the same initial concentration. The units should be M, and should be calculated to three significant figures.

Explanation / Answer

From experiment 1 to 2, you doubled the NO concentration and theinitial rate increased by 4 times.Thus rate is proportional to the square of NO concentration r~ k*[NO]^2From experiment 2 to 3, you double the O2 concentation, and theinitial rate increases by 2 timesThe rate is directly proportional to [O2]; r ~ k*[O2]Overall the rate is: r = k*[NO]2[O2]b) r has units of M/sk*[NO]2[O2] must have units of M/s[NO]2[O2] has units of M^3Thus k has units of M-2 s-1c)Experiment k = ra