Dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen. When the reaction takes place in carbon tetrachloride (CCl₄), both nitrogen oxides are soluble, but the oxygen escapes as a gas.

The rate of reaction (-Δ[N₂O₅]/Δt) can be measured by monitoring the volume of oxygen gas that is produced by the reaction. Quantitative analysis of the gas generated in such an experiment shows that the rate law is first order in N₂O₅ with a rate constant of 8.1 × 10^-5 s^-1 at 303 K. If the initial mass of [N₂O₅] is 0.032 g , how long does it take for the mass to decrease to 0.015 g?
Strategy

This problem looks different because we are given masses, instead of concentrations, but the concentration and mass are directly proportional. Because the problem involves concentration-time behavior, use the integrated rate equation. The rate constant is given, as are the initial mass (0.032 g) and the final mass (0.015 g). We can calculate t.

Transcribed Image Text:

NO5(soln) 2NO(soln) + O2(g) 2