Final answer:
To compute the resultant pressure when N₂O₄ decomposes into NO₂ upon heating, one must account for the stoichiometry of the reaction and the principles of the ideal gas law, considering the increase in number of moles of gas and the resulting change in pressure.
Step-by-step explanation:
The question at hand involves the calculations of resulting pressures in a chemical reaction when dinitrogen tetroxide (N₂O₄) is heated and decomposes into nitrogen dioxide (NO₂). Given that one mole of N₂O₄(g) at 300 K under one atmosphere is heated to 600K, resulting in a 20% decomposition by mass to NO₂(g), we are asked to calculate the resultant pressure.
To solve this, we must consider the stoichiometry of the reaction and the ideal gas law. Since 20% of N₂O₄ decomposes, this results in a 20% increase in the number of moles of gas due to the stoichiometry (N₂O₄ → 2 NO₂). This 20% increase in the number of moles would theoretically result in a 20% increase in pressure; however, since only a fraction of the original N₂O₄ converted to two molecules of NO₂, the total increase in moles is less than double. Factoring in the original pressure, the final pressure would be higher than 1 atm but would not exactly double due to the partial decomposition. The detailed calculations would involve using the ideal gas law and stoichiometry principles.