Question 1
Paper 2Hard12 marksAt 298 K, dinitrogen tetroxide gas dissociates to nitrogen dioxide gas in two sealed, rigid vessels. Each vessel initially contains only dinitrogen tetroxide. Figure 1 shows the structure of dinitrogen tetroxide.
The concentrations were measured over time. The final readings are treated as equilibrium concentrations for calculating
| Time / s | Run A [N₂O₄] / mol dm⁻³ | Run A [NO₂] / mol dm⁻³ | Run B [N₂O₄] / mol dm⁻³ | Run B [NO₂] / mol dm⁻³ |
|---|---|---|---|---|
| 0 | 0.0800 | 0.0000 | 0.1200 | 0.0000 |
| 20 | 0.0650 | 0.0300 | 0.0960 | 0.0480 |
| 40 | 0.0560 | 0.0480 | 0.0850 | 0.0700 |
| 60 | 0.0510 | 0.0580 | 0.0820 | 0.0760 |
| 80 | 0.0500 | 0.0600 | 0.0817 | 0.0767 |
| 100 | 0.0500 | 0.0600 | 0.0817 | 0.0767 |
| 120 | 0.0500 | 0.0600 | 0.0817 | 0.0767 |
Use Figure 1 to write a balanced equation, including state symbols, for the dissociation of dinitrogen tetroxide gas into nitrogen dioxide gas.
For Run A, calculate the ratio of the increase in [NO₂] to the decrease in [N₂O₄] between and
Write the equilibrium law expression for for the reaction in (a).
A researcher claims that is greater in Run B because its equilibrium concentration of NO₂ is greater. Determine whether the data support this claim. Include calculations for both runs and a conclusion.
A student argues that Run B cannot be at equilibrium because the concentrations of N₂O₄ and NO₂ are unequal. Evaluate this argument using the definition of dynamic equilibrium and the time data.