Description
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 284 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.
2.
| NO2(g) + CO(g)> NO(g) + CO2(g) |
The rate of the above reaction depends only on the concentration of nitrogen dioxide at temperatures below 225°C.
At a temperature below 225°C the following data were obtained:
| Time (s) | [NO2] (mol/L) |
| 0 | 0.520 |
| 1.10×103 | 0.481 |
| 2.75×103 | 0.433 |
| 4.12×103 | 0.400 |
| 8.25×103 | 0.325 |
| 1.65×104 | 0.236 |
Which of the following expressions for the rate law (either differential or integrated) are completely consistent with the above experimental data.
k[NO2]3 = -d[CO]/dt
ln([NO2]/[NO2]0) = -kt
k[NO2]2 = d[NO]/dt
-d[CO]/dt = k[NO2]2
1/[NO2] - 1/[NO2]0 = kt
| time (hr) | [N2O5](M) |
|---|---|
| 0.0 | 0.374 |
| 0.9 | 0.337 |
| 1.8 | 0.299 |
| 2.9 | 0.262 |
| 4.2 | 0.224 |
| 5.7 | 0.187 |
| 7.5 | 0.150 |
| 9.9 | 0.112 |
| 13.2 | 0.075 |
| 18.9 | 0.037 |
Reaction order:
Rate constant:
The effect of temperature on the rate of a reaction was studied and the following data obtained:
| k (s-1) | T (°C) |
| 1.91×10-4 | 5 |
| 2.25×10-4 | 7 |
| 3.07×10-4 | 11 |
| 3.58×10-4 | 13 |
| 4.84×10-4 | 17 |
| 7.49×10-4 | 23 |
| 1.06×10-3 | 28 |
| 1.22×10-3 | 30 |
It is known that the variation of the rate constant k with the absolute temperature T is described by the Arrhenius equation:
|
where Ea is the activation energy, R is the universal gas constant and A is the pre-exponential factor (units of the rate constant). Taking the natural logarithm of both sides affords:
|
For a plot of y = ln k versus x = 1/T, calculate the slope of the best straight line using linear regression.
Calculate the activation energy Ea.
Explanation & Answer
Review
Review
